What does research say?

Time is a finite resource for both students and teachers, and students and teachers often feel that a curriculum is crowded or overloaded. When addressing the issue of curriculum overload, curriculum designers frequently face questions such as: “Is it real or perceived?”; “How can we accommodate new demands from society in an already crowded curriculum?”; and “How can we ensure breadth and depth of learning that are both achievable within the time allocated in a curriculum?”.

Drawing on the existing literature to address these questions, curriculum overload can be analysed within four dimensions (Box 1).

Curriculum overload is also known as curriculum overcrowding or curriculum expansion (Voogt, Nieveen and Klopping, 2017[1]). It has been reported by researchers in both developed and developing countries, including Angola, Australia1, People’s Republic of China (hereafter “China”), England (United Kingdom), Indonesia, Japan, Kenya, Malawi, the Netherlands, New Zealand, the Philippines, Tanzania, Viet Nam, Wales (United Kingdom), Zambia and Zimbabwe (Majoni, 2017[2]).

It is important to note that curriculum overload is not the same as excessive workload for teachers and school leaders. Many factors other than the curriculum have an impact on teacher workload, such as changes in administrative structure or student population (Easthope and Easthope, 2000[3]).

This section introduces definitions of these concepts and presents policy considerations as well as research findings on possible impacts of these dimensions on students and teachers. It concludes with a list of areas where additional research can inform how to close knowledge gaps and better inform policies addressing the issue of curriculum overload.

Curriculum expansion refers to the tendency to include new content items in the curriculum as a response to new societal demands without proper consideration of what needs to be removed. Content expansion is cumulative and often occurs without attempts to remove prior content. Thus curricula become overcrowded over time (Alexander and Flutter, 2009[4]; Kärner et al., 2014[5]; Kuiper, Nieveen and Berkvens, 2013[6]; Voogt, Nieveen and Klopping, 2017[1]; Morgan and Craith, 2015[7]). This can occur due to new societal demands or pressure from lobby groups and a general desire to retain what has always been included in the curriculum. Such societal demands create new pressures on curriculum and teachers.

In our fast-changing world, there are increasing demands on the curriculum to reflect changes in society. Including emerging societal demands, such as digital literacy, financial literacy, literacy for sustainable development and computational thinking, can add a refreshing sense of relevance to what students are expected to learn (Kuiper, Nieveen and Berkvens, 2013[6]). For example, in Japan, the 2017 reform expanded the curriculum to cover content related to languages and computer programming and further increased instruction time, in response to growing demands for globalisation and algorithm/AI/computational thinking. In 2018, as part of its reference framework for quality learning, the European Commission highlighted a set of eight competencies deemed critical for lifelong learning:

  • literacy

  • multilingualism

  • numerical, scientific and engineering skills

  • digital and technology-based competences

  • interpersonal skills and the ability to adopt new competences

  • active citizenship

  • entrepreneurship

  • cultural awareness and expression (European Commission, 2018[8])

To compete for curriculum space, various actors and interest groups add pressure to reflect their agenda in the curriculum. Oates (2011[9]) also lists competing policy interests on what should be included in the core curriculum as one of the main reasons for overcrowding the national curriculum in England (United Kingdom). Curriculum may also become overcrowded when governments attempt to represent and accommodate all interest groups (Australian Primary Principals Association, 2014[10])2. Rawling (2015[11]) for example, points out how England’s geography curriculum has been increasingly used for political control, with politically sensitive topics such as climate change added or removed with little consultation with subject knowledge specialists, based on lobbying by various interest groups.

Such demands and pressures may contribute to curriculum expansion, as content priority is sacrificed to meet the political necessity of breadth in coverage (Australian Primary Principals Association, 2014[10]; Kirst, Anhalt and Marine, 1997[12])3. In England (United Kingdom), for example, the Cambridge Primary Review Report finds that, over time the “list of subjects has simply become longer and longer, and nothing has been removed to accommodate the newcomers” (Alexander and Flutter, 2009[4]). In the period between 1995 and 2010, the national curriculum had repeatedly expanded in response to new societal developments and challenges triggered by technologies, nutrition, media, environment and other fields of human activity (Oates, 2011[9]). Such curriculum expansion includes adding content updates, new subjects, new topics within subjects or new cross-curricular themes to the existing curriculum, and it contributes to curriculum overload, often setting overly ambitious learning goals.

Adding a new subject(s) is one of the high-stakes policy choice. Traditional subjects, such as reading, writing and literature, and mathematics, continue to appear as the main building blocks of curriculum in most countries. On average across OECD countries, around 53% of the curriculum in lower secondary education is devoted to four subjects: reading, writing and literature (15%); mathematics (12%); natural sciences (12%); and second and other languages (14%). The remaining time is distributed among “other” compulsory curriculum (38%) and compulsory flexible curriculum (9%) (Figure 1)4. This is true in most OECD countries, except in those where the curriculum does not prescribe learning time (e.g. the Netherlands and the United Kingdom), which gives schools and teachers considerable flexibility in terms of curriculum architecture (OECD, 2020[13]).

When assessing the risk of curriculum overload from adding a new subject, policy makers usually assess how this strategy will impact the experienced curriculum and how it will affect students’ total learning time. They need to weigh the benefits of adding subjects against the current demands of the curriculum.

Adding new topics within existing subjects is a policy alternative to adding new subjects. Embedding topics into what already exists is an option that is less politically charged, but this poses challenges for teachers. As a response to increasing societal demands, an increased number of themes and competencies are introduced in existing subjects (see “What kinds of cross-curricular themes do countries/jurisdictions articulate to accommodate new demands?”), without removing much content.

Figure 2 shows the number of teaching hours per year in lower secondary education across countries and economies and over time. Although it shows considerable variation across countries, a point worth noting is that there is relatively little change in terms of the number of hours of instruction within each country from 2000 until 2018.

Teachers are thus required to integrate new themes or more content within the same amount of teaching time. As a result, students may face the risk of shallow learning if they are not allowed sufficient time to explore new concepts in a meaningful way.

Curriculum defines not only what students learn in school, but also how school can help them learn for life (OECD, 2019[14]; Abiko, 2019[15]). If students can see a sense of purpose in learning in their classroom (i.e. see the relevance of learning to what is needed in real life), they are likely to feel more motivated to learn and acquire the types of competencies teachers are trying to help them develop (Eccles and Midgley, 1989[16]). Their interest and engagement levels may be naturally higher than when learning traditional academic subjects. Greater levels of motivation can certainly facilitate student learning (Department of Education and Skills, 2015[17]). Students may feel a sense of relevance when the curriculum is more in line with real-world demands.

But teachers who have not received proper training may not know how to support students in these emerging areas. For example, at a time when digital skills are no longer considered merely “nice to have”, but are rather deemed to be a core “must-have” competency for the future (OECD Learning Compass 2030 (OECD, 2019[18])), computational thinking and programming gain prominence in curriculum reform. However, teaching such skills requires specialised training. When teachers don’t have that training, they are likely to feel overwhelmed and helpless (Rutherford, Long and Farkas, 2017[19]). Even well-prepared teachers may experience a drop in their sense of self-efficacy in some of these emerging areas if they have not received sufficient support through either their initial teacher preparation programme or targeted professional development activities (Zee and Koomen, 2016[20]).

For example, data from the OECD Teaching and Learning International Survey (TALIS) reveal that supporting student learning through the use of digital technology is still a challenge for a large proportion of teachers who participated in the survey, compared with other typical skills (Figure 3).

Japan has also learned from past experience that expansion of content has additional complexities. The modernisation of subject content at the time was highly influenced by the work of J. S. Bruner’s The Process of Education (Bruner, 1960[21]). The amount of learning contents reached a peak in the National Curriculum Standards revised from 1968 to 1970, which was pointed out that the Standards overemphasized on intellectual education. Subject content was partly redesigned to introduce the newest findings of natural and social sciences into school curriculum. Anecdotally, it has been reported that students struggled with the new content. The reasons for such unintended consequences are still unclear, but they seem to be linked to the levels of difficulty of the new content and the lack of teacher preparation for such new demands (Abiko, 2008[22]).

As noted earlier, resistance to accommodate new demands in curriculum partly comes from the difficulty in removing existing contents and subjects (Alexander and Flutter, 2009, p. 17[4]). Content overload refers to the excessive amount of content to be taught and learned in relation to the time available for instruction (Boersma, 2001[23]). To avoid content overload, key considerations during curriculum redesign include: the overall structure of the curriculum; the number of subjects/topics; the quantity and quality of learning time; the pitch of what to include; and the size and language of curriculum documents.

A poorly designed curriculum that lacks clear structure and coherence can increase the sense of content overload. When it is difficult to navigate through the curriculum, teachers are more likely to misunderstand its intent and use it ineffectively.

New Zealand has been considering how curriculum can be better designed to assist understanding and implementation. Drawing on the work of Graeme Aitken (Aitken, 2005[24]), the Ministry of Education put forward the following six criteria for evaluating the design of a curriculum statement (Ministry of Education (New Zealand), n.d.[25]):

  1. 1. It is logically structured around a clear and unambiguous purpose.

  2. 2. It clearly explains the rationale for change.

  3. 3. It incorporates misconception alerts.

  4. 4. It acknowledges teachers’ existing understandings and integrates them into the new document.

  5. 5. It maximises internal coherence and minimises complexity.

  6. 6. It clearly connects abstract ideas to spatially contiguous detail and examples.

As noted above, what happens in a school is wider and more diverse in form than the stated content of a national curriculum. Content overload arises during curriculum redesign and becomes manifest during curriculum implementation (Boersma, 2001[23]), and it can be experienced differently by students, teachers and staff in the school (see “What is perceived overload? How does it affect students and teachers?”).

The main challenge is when a curriculum contains an excessive number of subjects and/or topics within individual subjects (Voogt, Nieveen and Klopping, 2017[1]; Kärner et al., 2014[5]; Australian Primary Principals Association, 2014[10]; Haug, 2003[26]; NCCA, 2010[27]; FitzPatrick and O’Shea, 2013[28])5. Excessive content is commonly measured based on the analysis of instruction time allocated per content item (Schmidt, Wang and McKnight, 2005[29]; Schmidt, Houang and Cogan, 2002[30]). Research in cognitive science suggests that cognitive overload, associated with increased mental stress and reduced relaxation, results in decreased student performance (Fraser et al., 2012[31]).

Content overload is often driven by unrealistic expectations for retaining both breadth and depth of content within the allotted space and time. Breadth means the number of subjects included in the curriculum and the number of topics to be taught within subjects. Depth means the degree to which students explore and understand what they are learning.

Achieving an appropriate balance between breadth and depth in curriculum content remains a persistent unresolved issue in education reforms of many countries (Alexander, 2009[32]), with direct consequences for students’ learning. Coverage of broad knowledge content is often prioritised over in-depth learning, which results in “more learning” rather than “deeper learning” (Schmidt and Houang, 2012[33]).

Having fewer topics to be covered in more depth in a curriculum often raises concerns about lowering standards of student achievement (UNESCO, 2002[34]). However, research suggests that studying fewer topics in greater depth helps students to develop richer understanding and higher-order thinking that can be transferred beyond specific subjects to new learning areas and new problems (Coker et al., 2016[35]; Schwartz et al., 2009[36]). Schwartz et al. (2009[36]), among others, argue that a focus on learning in depth may improve not only student academic achievement but also student satisfaction (Laird et al., 2008[37]).

Countries/jurisdictions include a wide variety of subjects in their curriculum. At the subject level, the secondary school curriculum of post-Soviet Ukraine in the 2000s included 17 different subjects, with as little as one hour of instruction per subject per week, while an average secondary school student in Uzbekistan studied as many as 28 different subjects (Moreno, 2007[38]). At the level of content items, a high number of topics within subjects has been cited as a major source of curriculum content overload in the United States. While eighth-grade mathematics textbooks in high-performing countries, such as Japan and Singapore, cover about 10 topics, those used in the United States cover as many as 30 topics (Schmidt, Houang and Cogan, 2002[30]). The mathematics and science curriculum in the United States has been criticised as “a mile wide and an inch deep”. This approach to curriculum has been found to lead to poorer outcomes than in other countries in terms of student achievement (Schmidt, Houang and Cogan, 2002[30]; Schmidt and Houang, 2012[33]; Schmidt, Wang and McKnight, 2005[29]).

An increasing number of countries/jurisdictions have made a clear distinction in curriculum between “key concepts” and “facts and procedural knowledge” to facilitate deeper learning. Accordingly, the concept of “big ideas” (similar to “key concepts”, “fundamental ideas” or “essential learning”) commonly appears in curricula as a way to highlight essential ideas that, approached from different angles, are crucial to multiple learning areas in both OECD countries and partner economies (Table 1). The simplicity of indicating clearly what are the “big ideas” in a learning area can help teachers remain focused when deciding what to prioritise from the more exhaustive curriculum without being overly prescriptive at the level of content items.

British Columbia (Canada) adopted this “big ideas” model in their curriculum redesign (Figure 4). The curriculum was designed by curriculum development teams that included teachers early in the process. The teams worked together through the revisions, which resulted in a progression of big ideas, curricular competencies and content for each learning area.

Unique to their approach is a clear indication of which content is to be prioritised. In this approach, greater value is placed on competencies and content that transfer across contexts and on a conscious effort to identify what is considered essential learning, among many items that could potentially be present in an exhaustive curriculum. This means, for example, prioritising higher-order concepts and ideas that are fundamental and enduring within a disciplinary body of knowledge and those that possess greater transfer value across disciplines and contexts.

This transferability supports the learning process across subjects in such a way that what students learn in science, for example, might support what they will be learning in social studies. This can be illustrated by the concept of “change”, which in the British Columbia curriculum is considered to be transferrable across the subjects of arts education, social studies, science, health education/physical education and mathematics (Table 2).

The New Zealand curriculum provides only high-level guidance. Subject-specific content is not mandated, although key topics/focus areas are identified. For example, the following key topics are included in the Science learning area: New Zealand flora and fauna; interdependence of geosphere, hydrosphere, atmosphere and biosphere; and physical phenomena such as light, sound, heat, motion, waves and forces. In a few instances, the government advises on the importance of including specific content. But, in general, most decisions regarding the selection of topics within each learning area are left to schools guided by the structure of the learning area and the achievement objectives set out in the national curriculum.

In New Zealand, the national curriculum is composed of the New Zealand Curriculum and Te Marautanga o Aotearoa (TMOA). Both documents are the result of broad societal consultation, including the views of teachers, principals, school boards, parents, employer representatives, curriculum associations, education sector bodies, academics and the wider community. TMOA is a guide to teaching practices in Māori-medium schools in New Zealand. It is merely a framework, not a complete teaching plan or teaching programme. Here again, schools need to develop their own school-based curriculum. For example, programmes may be planned by learning area, topic or context. Both the New Zealand Curriculum and TMOA succinctly describe what is considered essential for learning. Schools are expected to develop and design their own curriculum based on broad specifications.

In the United States, at the suggestion of the National Science Foundation, a number of award-winning scientists convened to discuss what could be considered “fundamental ideas” in science and how they could be the basis for a new science curriculum. The result was The “8+1” Fundamental Ideas of Science (Figure 5). These fundamental ideas represent answers to three questions:

  • How do we know what we know?

  • What are things made of?

  • How do systems interact and change?

The “+1” (meaning “Inquiry”) is related to essential ideas, such as probability, scientific reasoning, scales, measurement and orders of magnitude. The new curriculum could in turn embrace the principles of focus, rigour and coherence (Schmidt, 2011[39]). As design principles to guide curriculum construction, focus suggests that a relatively small number of topics should be introduced to ensure deep, quality learning; rigour suggests that topics should be challenging and enable deep thinking and reflection, which is not to be confused with rigid or inflexible design; and coherence suggests that topics should be ordered in a logical way to create a progression (OECD, 2019[40])

In mathematics, some countries/jurisdictions are also shifting away from disconnected factual knowledge towards more holistic conceptual understanding to make mathematical learning more meaningful to students. Word problems have long been used to convey real-world situations, which help students understand how mathematical concepts can be used outside of school (OECD, 2014[41]). Examples include problems on purchasing furniture with a discount and determining someone’s age based on a relationship to the age of others.

Emerging 21st century challenges are also reinforcing the need to foster a deeper conceptual understanding of mathematical content as opposed to rote learning. Addressing these challenges requires equipping students to think mathematically (OECD, 2014[41]). Many countries are fostering conceptual understanding by giving students opportunities to learn different kinds of formal mathematical concepts, such as calculus, complex numbers and trigonometry.

Increased mathematical reasoning and the ability to apply problems in the real world have to go hand in hand. Nonetheless, in already crowded curricula, it is often difficult to make sufficient room for opportunities to learn for both and countries/jurisdictions need to set priorities. Deeper understanding of mathematical concepts is linked to being able to apply mathematical reasoning and problem solving. While word problems are often easier for teachers to apply, they may be more prone to rote learning than to deep learning.

Figure 6 shows how countries/jurisdictions seem to be making different choices in their mathematics curriculum based on students’ reported exposure to either word problems or formal mathematics, which supports conceptual understanding. For example, students in Shanghai (China), a high-performing PISA jurisdiction, report the greatest exposure to conceptual understanding through formal mathematics while being much less exposed to word problems among participating countries and economies. In contrast, Iceland shows the opposite pattern: their students are frequently exposed to word problems with comparatively few chances of being exposed to formal mathematics. When faced with limited time, the choices of what to prioritise can make a difference for the type of learning students will experience and how enduring their learning is within and across disciplinary boundaries.

Reinforcing the notion of “big ideas”, “fundamental ideas”, and “conceptual understanding’ is the concept of “essential learning” as seen earlier in the case of the British Columbia new curriculum. In their framework, the definition of what constitutes essential learning varies by learning area, but it should result from a reflection on what students should know (knowledge, facts) within a learning area, what essential ideas students should understand and use in other contexts, and what students should be able to do in a learning area or across learning areas as a result of learning at a given grade level. The principles6 include the following (OECD, 2017[42]):

  • Pay close attention to the important concepts and big ideas in each area of learning to support the application and transfer of essential learning.

  • Ensure that core competencies are explicitly considered in the renewed curriculum to support deeper learning and the transfer of key skills and processes to new contexts.

  • Limit the amount of prescription while ensuring a solid focus on essential learning.

  • Stress higher-order learning, giving emphasis to the key concepts and enduring understandings (big ideas) that students need to succeed in their education and their lives.

  • Allow for flexibility and choice for teachers and students.

Focusing on big ideas and essential learning is one of the common strategies used by countries to mitigate content overload. This will also help facilitate effective learning by keeping the developmental needs of children in mind.

Making connections across subjects (e.g. through cross-curricular themes and competencies) can be an effective strategy of reinforcing content and deep learning (Hurley, 2001[43]). Early childhood education curriculum is not organised by subjects in the first place and, thus, it does not need to break down silos between subjects (Jenkins et al., 2019[44]). However, secondary education teachers may not feel prepared to implement cross-curricular connections, even immediately after their training (Parker, Heywood and Jolley, 2012[45]). In primary education, it is easier to implement the approach as the same teacher teaches all subjects. However, given accountability measures, primary teachers may also find making these connections a challenge (Brand and Triplett, 2012[46]).

Project-based learning can be a model to integrate different subjects and make meaningful connections. These are cross-curricular projects wherein students solve a real-world problem or participate in a group project. They make connections across subjects like science, mathematics and writing, because they need to conduct the project, write up and present material, and solve the problem. Indeed, such approaches can improve learning and attitudes, through the group-oriented nature of the work (Kaldi, Filippatou and Govaris, 2011[47]). Various approaches and methods can be used to facilitate learning, but project-based learning often feels more relevant to students and can be effective at engaging them (Kokotsaki, Menzies and Wiggins, 2016[48]), while there is no conclusive evidence on the impact of such practices on actual learning outcomes.

Research in neuroscience highlights the value of staging new content so that the brain can appropriately organise information for deeper understanding (Simon and Tzur, 2004[49]; Simon et al., 2010[50]; Lehrer and Schauble, 2015[51]; Penuel and Shepard, 2016[52]; Shepard, Penuel and Pellegrino, 2018[53]; Giedd, 2004[54]). When introducing new content in a curriculum, prominent attention should be given to staging or sequencing the new topics, taking into account students’ stress (e.g. feeling overwhelmed by too many materials that are too difficult for them) or boredom (e.g. repeating materials they already understand).

Some repetition of topics is deliberate. It is built into a curriculum to reinforce students’ understanding of the ideas or concepts they are learning. If the prerequisite notions have not been properly taught or understood, this may hinder their understanding of new content. This could occur by not paying sufficient attention to what students are presumed to know and what they have actually understood at the start of each grade or level.

Other repetition of topics is considered duplication of content. This is reported as a challenge by countries/jurisdictions such as Australia, Korea and the Netherlands. Some have started to limit such duplication by reducing content or taking an interdisciplinary approach. Most others report using learning progressions (Table 3). In particular, Estonia, Ireland and New Zealand adopted the approach to recognise the non-linear nature and individual differences in learning progressions, rather than organising learning linearly by grades. This is often called a “spiral curriculum” (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

Several report challenges not only in content duplication but also in the disconnect in learning progression between different levels of education. One of the strategies to address the repetition of content and disconnect across grades, is to redefine leaning goals by learning stages rather than grades, such as by primary or secondary cycle, as well as by achievement levels or by other factors such as discipline or level of complexity. This allows opportunities to review and repeat content throughout the different grades in accordance with the level of the learner’s development (see “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?” section for country examples).

Curriculum progression may refer not only to the transition from simple to complex ideas. It may also be used to help students move from concrete examples to more abstract levels of thinking. These progressions represent a long-term plan of trajectories for students’ learning over the years, rather than a grade-by-grade approach and, as such, they are more of an adaptive process (Confrey, 2019[55]).

When curriculum frameworks for each level of education are supported by a coherent, longer span of age coverage, alignment across different education levels becomes easier to achieve. Without such a framework, curriculum committees at each different level of education are likely to make decisions considering the age group specific to that level. This often results in fragmentation, redundancies and inconsistency of topics across levels of education.

Furthermore, it is important to be mindful of students’ development across education levels. Curriculum that is primarily built on the priorities of subject areas rather than on what is developmentally appropriate is likely to overlook grade-level transitions and could allow repetition to persist without considering or assessing the needs of students (Eccles and Midgley, 1989[16]). Students may experience a decreased sense of self-efficacy, along with negative attributions to explain failure in the face of new learning (Schunk and DiBenedetto, 2016[56]; Zhen et al., 2010[57]).

Students may start to believe that they are not smart enough to learn the new material (Wigfield et al., 1997[58]). This can lead them to simply stop trying and to develop fixed ideas rather than an enquiring mind (Weiner, 1972[59]). Repeating topics can help students bridge old and new learning. Focus, rigour and coherence remain the critical design principles when considering the amount, level, and sequencing of topics to include in a curriculum (see Overview Brochure7).

In Denmark and Sweden, for example, the curriculum framework encompasses primary and lower secondary education in a coherent way, considering and accommodating learning progressions (Figure 7). This helps to avoid fragmentation and content overlaps which can put unnecessary pressure in curricula, increasing curriculum overload and potentially causing students to disengage.

Furthermore, some countries/jurisdictions, such as Denmark, Finland and Japan, recognise that learning starts at age 0 by extending the curriculum framework to cover the early years (Figure 7). This approach contributes further to ensuring alignment between school requirements and children’s natural learning process and developmental stages. This way, the curriculum in early childhood, primary and secondary education can be seen as a continuum to prepare students to navigate future challenges with a progressive approach.

As seen earlier, content overload refers to excessive content expected to be taught in a limited amount of time. The number of mandated instruction hours per school year therefore sets the limits within which content is to be taught. When there is too much content planned and insufficient time to teach everything, the quality of teaching may suffer, in the absence of strategic decisions about what to prioritise.

Empirical evidence on the relationship between school instruction time and student achievement is inconclusive. Added instruction time has been found to provide more learning opportunities and to correlate with higher academic achievement (Rivkin and Schiman, 2015[60]; Huebener, Kuger and Marcus, 2017[61]; Andersen, Humlum and Nandrup, 2016[62]). Extra instruction time has also been shown to help lower-performing students to catch up with higher-performing students (Rivkin and Schiman, 2015[60]; Lavy, 2015[63]). However, more hours of instruction do not automatically translate into better scores and quality learning (Alexander, 2009[32]; FitzPatrick and O’Shea, 2013[28]; Alexander and Flutter, 2009[4]; OECD, 2014[64]).

Furthermore, a growing body of research suggests that the relationship between hours of learning and student performance is not linear (Cattaneo, Oggenfuss and Wolter, 2017[65]; Huebener, Kuger and Marcus, 2017[61]). The 2015 report of the OECD Programme for International Student Assessment (OECD, 2016[66]) also found that time spent on learning, both within and outside school instruction time, does not correlate to students’ academic performance (Figure 8). Transferring uncovered curricular content to students’ personal time as homework also has been reported to have a potentially negative impact on students’ mental and physical health (Chraif and Anitei, 2012[67]).

Compromising students’ well-being with excessive learning hours or excessive homework is also a common challenge when addressing curriculum overload (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”). This challenge needs to be balanced with the benefits of homework, such as the long-term development of children’s motivation, strategies for coping with mistakes and setbacks and the time for children to develop positive beliefs about achievement (Bempchat, 2004[68]).

If teachers feel pressured to teach everything in an overloaded curriculum, it may also lead them to teach a shallow version of the curriculum or to leave what cannot be covered in school instruction time for students to pick up in their personal time outside of school. Content overload may also be further challenged by or may, in some instances, encourage the use of private tutors, also known as shadow education (Bray, 2011[69]). In Asia and parts of Europe, it is common for students to participate in tutoring after the school day, either as a supplement to their typical day or to help students with content from their school work. In Japan, for example, this is called juku, while in Korea, it is known as hagwon.

In some countries/jurisdictions that have undergone curriculum redesign or otherwise have an overloaded curriculum, parents sought out additional help when students could not finish the material. In Malta, for example, teachers expressed the need to finish the curriculum at all costs, even if students could not follow the material (Budiene and Zabulionis, 2006[70]). Elsewhere, the trend is for tutors to supplement with extra material, potentially dominating students’ already burdened lives and contributing to adverse psychological and educational outcomes (Bukowski, 2017[71]). There is also a significant gap in use of tutoring services by socio-economic status, with higher-income families being more likely to use such services, again, contributing to educational disparities (Bray, 2020[72]).

Acknowledging that students are all different and they learn differently, including their prior knowledge and pace of learning, it is essential to anticipate the needs of teachers for guidance on priorities, as mentioned earlier. Teachers otherwise may attempt to cover everything for all students and some students, in particular low-performing students, may feel overwhelmed by the volume of content in any given learning unit. To meet expectations, they may need to spend a lot of extra time studying outside school hours on top of regular extra-curricular activities. This can make it difficult for them to participate in other activities that are important for full development and fostering a balanced lifestyle, such as time to socialise and be with friends, time to play, time to exercise and time to sleep (Marhefka, 2011[73]).

Student voice is critical in understanding overload as countries/jurisdictions seek to avoid it. Box 2 explores student perspectives on their educational experiences in relation to learning hours. In addition to learning within school, many participate in other activities and have other demands on their time. They report being busy and eager to be able to spend more time on topics that engage them.

Excessive content may also require teachers to spend extra time outside of teaching hours to prepare lesson plans and assess students’ progress, including grading and providing individual feedback to students. Furthermore, the “mile-wide-and-inch-deep” approach mentioned earlier can lead to disengagement among students and teachers. Some repetitions are deliberately built into a curriculum for students to reinforce and deepen their understanding of concepts or ideas that they are learning in a developmentally appropriate sequencing. However, topics that appear repeatedly within and across disciplines without a clear purpose are likely to create negative perceptions and experiences among students and teachers (Schmidt, Wang and McKnight, 2005[29]; Schmidt, Houang and Cogan, 2002[30]).

Teachers in countries/jurisdictions where their administrative load is already significant (which is not uncommon in Asian countries, such as Korea and Japan) may end up investing time outside of working hours to meet the expectations. Lesson preparation and administrative tasks related to the curriculum may reduce the time actually consecrated to teaching. If only a small amount of their time is actually spent teaching, teachers’ sense of overload may further increase. Of their working time, they only spend an average of 53% on teaching (Figure 9).

An unsustainable workload is also associated with teachers' decisions to leave the profession (Torres, 2016[74]). In addition, the non-teaching-related workload of teachers or the time devoted to preparing lessons or performing administrative duties is strongly related to burnout, whereas teaching-related workload has a more modest relationship (Lawrence, Loi and Gudex, 2019[75]). The more responsibilities teachers have, the more time they will need to spend away from their core activity of teaching. For teachers to feel supported and remain in the profession, it may be critical to monitor the time they spend on their work outside of the classroom.

Curriculum overload can, therefore, threaten teachers’ ability to cope with expectations, impact their levels of satisfaction with the profession and deprive them of their sense of agency by leaving no room for their own creativity. It can also affect their individual well-being, through chronic fatigue due to excessive working hours.

Content overload is also caused when overly ambitious learning goals and student outcomes are set in a curriculum without careful consideration for the allotted space and time. Additional sources of content overload can arise based on how they are translated into syllabuses, textbooks, assessment materials and homework. A fundamental challenge for curriculum designers is to define the right “pitch” in the curriculum. This means achieving an appropriate level of aspirations, ambitions and challenges for all students while recognising the differences among students’ learning progressions and their prior knowledge and skills. Content overload is thus a relative concept, as it depends on who uses the curriculum.

Neuroscience research confirms what many teachers already know from experience, that the brain can respond to stimuli and benefit more from learning if content and the learning environment are aligned for optimal stimulation and reinforcement (Dubinsky, Roehrig and Varma, 2013[76]). When students are bored or stressed (due to excessive demands, fear of failure and repeated information), their metabolic responses may block information from being processed in the brain, with clear negative implications for learning (Dubinsky, Roehrig and Varma, 2013[76]; Goswami, 2008[77]).

The challenges when defining the pitch for curriculum include trade-offs between aiming higher and focusing on essentials, and ensuring opportunities to learn and opportunities to succeed.

A curriculum without high aspirations or challenging contents can lead to disengagement among high-performing students, while a curriculum with overly ambitious aspirations and too much content can risk disengagement among low-performing students, leaving them to fall behind. There is no silver bullet and no single answer to determine the right pitch for a curriculum that can capture the needs and aspirations of all students.

Japan, for example, reduced content and decreased the amount of instruction time in its 1998 reform to ease anxiety among students and parents about intensified competition for university entrance. The goal was to leave no student to fall behind and to enhance the quality of learning time, but the reform was misunderstood as a lowering of standards. In response to a backlash to that reform, the 2008 curriculum increased both content and instruction time.

Hong Kong (China) reported that the curriculum set at the high end of the standards was pitched for the full ability spectrum of students, but the curriculum allows adaptations to cater to the individual needs of students. Higher-ability students might cover all of the content, while lower-ability students may study only the foundational elements rather than all content. However, many schools and parents that were not accustomed to such an idea would encourage all students to study all content items. As a result, weaker students found that studying all of the curriculum content was too heavy (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

When expectations are unrealistic, some teachers may decide to partially cover the content specified in the curriculum while assigning the remaining parts for students’ self-learning through additional homework assignments. As noted earlier, this can have negative consequences for students’ well-being.

When excessive content sets out unrealistic expectations, learning goals end up not being met as intended. In Chile, for example, research on the coverage of the curriculum reveal that a majority of courses offered in mathematics and language do not cover 100% of the minimum mandatory objectives (Ramírez, 2006[78]). If students will need literacy and numeracy as a prerequisite to learn new content in later grades, students whose teachers did not cover the previous contents are likely to miss out on opportunities to learn. The more fundamental concepts and skills these students miss, the higher the chances are that they will also miss out on opportunities to succeed, at in later stages in life. Therefore, core foundations should be considered as fundamental priorities in the curriculum.

Children from socio-economically disadvantaged backgrounds in particular may miss out on these key opportunities. Research from the United States has shown that poor reading skills of third-grade students, who do not have access to reading materials or opportunities to learn to read at home are associated with lower chances of students graduating from high school (Hernandez, 2011[79]; Sparks, 2020[80]). Such research findings reinforce the importance of public policies, including the purpose and function of a curriculum in addressing inequity.

When selecting what subjects/topics to include in a curriculum and in what order, it is important to consider each subject-specific learning goal as an independent block that should develop only in a linear sequential order, but rather as an interdependent piece of a puzzle which can help a student to learn. The piece then fits within and across different subjects in a developmentally appropriate sequential order. The sequence should consider the nature of each subject; some subjects require a linear and hierarchical order when learning concepts for the developmentally appropriate sequencing (e.g. mathematics) and others (e.g. history) do not assume sequential or hierarchical progression but learning is measured by mastery of levels of complexity within each skill, which can occur in a concurrent and interrelated manner (Zarmati, 2019[81]; Confrey, 2019[82]).

Education is a complex system with students in classrooms influenced by their teachers, schools, communities, local and regional educational agencies within states; all of which have an influence on the content, pedagogy, and outcomes as a part of a larger ecosystem. An ecosystem approach to curriculum design (see the Overview Brochure) is still new, and thus there is not yet a solid body of research. However, some countries/jurisdictions have started to explore this concept as a new form of spiral curriculum, as in Estonia, Ireland, and New Zealand (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

Content overload may also be related to the excessive size of curriculum-setting statutory documents (i.e. the number of objectives, subjects and pages in which the curriculum is defined and elaborated) (Australian Primary Principals Association, 2014[10]; FitzPatrick and O’Shea, 2013[28]; Haug, 2003[26]; Voogt, Nieveen and Klopping, 2017[1]; ACARA, 2018[83]; NCCA, 2010[84]; Hong and Youngs, 2019[85]; Sousa, 2013[86])8.

The number of pages and words in curriculum documents can indicate overload: “…it is a strong measure of general overcrowding such that, if teachers have to read a greater number of pages to understand the curriculum, they will take longer to understand what is expected of them” (Australian Primary Principals Association, 2014, p. 4[10])9.

For example, the 1999 Irish primary school curriculum content was elaborated in 23 books amounting to over 3 650 pages (FitzPatrick and O’Shea, 2013, p. 126[28]). As of 2014, Australia’s curriculum comprised over 1 700 pages (Australian Primary Principals Association, 2014[10])10. This rendered the curriculum difficult to understand and manage, with teachers struggling to divide instruction time to cover all subjects while trying to meet the needs of all students (FitzPatrick and O’Shea, 2013[28]).

Some countries/jurisdictions have been able to appropriately adjust their curriculum. Norway reduced the volume of curriculum documents, used clearer language, and made priorities clearer when reducing content. On the other hand, Ontario (Canada) experienced a distinct challenge. Although the size of the mandatory curriculum itself was short, teachers did not consistently make a distinction between the core curriculum and optional guidelines. That led to the misunderstanding that there was more content to teach than what was actually in the mandatory document (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

Another experience commonly reported by several countries/jurisdictions is that, even when a national curriculum can be stated in a short, concise form, the brief form can actually create overload and incoherence at the school level. Perceived overload is mainly due to a lack of specific details and clarity on what should be taught and to what depth and the task of developing a working curriculum at local and school levels. Uncertainty, anxiety and ineffectiveness all can be high, especially for teachers, when there is much local political pressure without proper support mechanisms (Kyriacou, 2011[87]).

Excessive content is also measured based on end-user feedback from teachers, administrators and students (Kuiper, Nieveen and Berkvens, 2013[6]; Silver et al., 2011[88]). Thus, it is critically important to distinguish between actual and perceived overload. Policy makers first need to establish facts, by asking such questions as:

  • Is overload “real” or “perceived”? (as discussed in the section above on content overload)

  • If the overload is real, what factors might explain it?

  • If the overload is a perceived, whose perception is it? And what are the possible sources or roots of such a perception?

If the overload is real, one possible solution is to reduce content, as in Korea, Norway and Singapore. If the overload is real, with a dilemma in trade-offs between schools and national authorities in responsibility for curriculum design, as in Finland, Norway, and New Zealand, the country-specific context affecting that balance must be addressed.

If the overload is a perception, different solutions are possible, depending on the country-specific context. For example, it was necessary to address assessment overload in Australia11, mistrust in frequent curriculum changes in Japan, and misunderstanding about focusing on essentials and lowering standards in Portugal.

Once perceived overload is identified as an issue, policy makers can consider ways to strategically manage stakeholders’ perceptions. In curriculum redesign processes, it is of critical importance to anticipate and manage potential unintended processes and consequences. For example, the National Council for Curriculum and Assessment in Ireland suggests perceptions of overload as follows:

Much of what we know about curriculum overload comes from teachers. Some observers may question the extent to which the overload phenomenon is imagined, perceived or real. (…) National and international experience and evidence (…) suggests that the overload issue is very much a reality for teachers, and paradoxically, is often an unintended consequence of education reform.” (NCCA, 2010, p. 7[27]).

In fact, curriculum overload is an intricately intertwined mix of reality and perception. To reduce the risk of unintended consequences, it is very valuable to learn more about possible consequences through both research and the experience of peer countries/jurisdictions. The main factors driving perceived overload include: the number of subjects/topics to cover in the allotted time; the frequency, focus and types of assessments, textbooks, learning materials and homework; the size and volume of curriculum documents; the structure and coherence of the curriculum; and the lack of readiness for reform or reform fatigue.

Too many subjects/topics to teach within a specific time frame can cause actual content overload, but it also be a question of perception. Based on end-user feedback, teachers’ perceptions of having “too much to teach” within the available instruction time can be one of the main criteria for identifying curriculum content overload (Australian Primary Principals Association, 2014[10])12. Finland sees overload stemming from this too, citing criticism from teachers that its previous National Core Curriculum had more to do with “heaviness” created at the local level than requirements outlined in the national document (See “What types of challenges do countries face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

Teachers who perceive that there are too many topics in their subject curriculum may feel pressured to provide extensive coverage of the content required by the curriculum. This perception may lead to shallow rather than deeper learning for students. This, in turn, may frustrate teachers and sap their motivation and sense of purpose, i.e. teacher agency, as described in the OECD Learning Compass 2030 (OECD, 2019[14]). Ultimately, they may be unable to exercise professional judgment.

On the other hand, teachers may make individual decisions on what they can realistically teach within a given learning unit or cycle. This could result in discrepancies in the taught curriculum across classrooms and schools and even the entire system.

Perceptions about content overload are also driven by a sense of assessment overload. As students do not read the learning goals in the written curriculum document itself, they are most likely to perceive or experience examinations and assessments as the most visible learning goals. Indeed, students often only see assessments as the curriculum (Ramsden, 1993[89]). Assessments drive what students perceive as being important to learn (Brown, Bull and Pendlebury, 2013[90]) and what is eventually retained in a curriculum across redevelopment cycles (Kärkkäinen, 2012[91]).

Although the curriculum may encourage development of more holistic skills alongside content knowledge, when exams are heavily based on mastering content, students will likely be steered towards what gets tested at the expense of other important development areas. This “teaching to the test” can mean that what could be mastered will be compromised by what will be tested (Jennings and Bearak, 2014[92]). This phenomenon is more commonly seen at the high school level as students approach their transition to college, but it can also be observed in early grades.

The types of assessments matter as well. Reliance on examinations, particularly high-stakes exams to pass to another grade or for college entrance, can cause significant anxiety, as early as in primary school (Segool et al., 2013[93]). Moreover, test anxiety decreases performance in school (McDonald, 2010[94]). Depth of learning and retention may also not be as great as that achieved through other forms of assessments or engagement with learning material (Hackthorn et al., 2011[95]). When curriculum relies on exams, especially as the sole assessment technique or as a gatekeeping tool, students’ well-being can suffer.

Finally, curriculum standards and assessment must be aligned. Without clear progression and scaffolding of the curriculum, students may struggle to learn (Heritage, 2008[96]). Having the time and opportunity to learn could be further challenged in an overloaded curriculum.

The size, volume and details of a curriculum can cause actual content overload, as discussed earlier, but they can also create the perception or the experience of overload among students, teachers and principals (Voogt, Nieveen and Klopping, 2017[1]).

Students are unlikely to know much about the sheer volume of the physical curriculum and related documents, but they can be a burden for teachers. At each cycle of education reform and curriculum redesign, an excessive number of pages in new curriculum documents may signal to teachers that the curriculum is overloaded. An immediate negative reaction to very large documents may set the scene for a perception of curriculum overload, even if the curriculum avoids an overly prescriptive tone and is careful to include detailed guidance to teachers on how to implement it (See “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?”).

Perceptions about curriculum overload are also created by excessive use of textbooks, learning materials and homework. For example, too much homework that is not explained well or does not have clear links to course material, can be boring, demotivating, and ineffective in helping learning (Bryan and Burstein, 2004[97]). The content and volume of textbooks can also be excessive and not appropriately modified to a new curriculum or local contexts and culture (Wang, 2014[98]). This makes them difficult for teachers to use and overwhelming for students and parents. Textbooks can have a cultural bias too, making them less accessible to all learners (Wang, 2014[98]; Ndura, 2004[99]). Easy-to-use teaching materials can also help ensure that a curriculum is implemented as intended and reduce teacher frustration (Kärkkäinen, 2012[91]).

Curriculum documents should support teachers to effectively convey and support the curriculum and learning by their students. Similarly, textbooks should be a resource for students to reinforce learning in the classroom and convey material clearly. However, when the curriculum is overloaded or textbooks are not appropriately modified, teachers can be frustrated and students overwhelmed.

Teachers’ perceptions on curriculum change in general may accelerate or alleviate their perceptions on content overload. They are not always ready for reform. Finland reported that teachers involved in developing curricula tend to add rather than replace content, observing that they want to add new content in response to changing times and needs, but they hardly let go of any of the previous goals or content.13 This suggests that teachers may perceive content overload differently depending on their own preparedness for curriculum change and readiness to digest and use any new support materials.

Busy teachers may not find the time to review such long documents and fully understand the new curriculum. They may become dismissive of the latest reform, preferring instead to resort to their previous classroom practices and lesson plans as something more feasible and long-standing. They may quickly lose interest in better understanding the new curriculum and discount it as one more transitory reform cycle that is likely to be short-lived. These are some signs of reform fatigue among teachers that can be sparked simply by the physical presentation of the curriculum (Dilkes, 2014[100]). However, mechanisms and processes can be put in place to effectively manage change and provide additional support and coaching to teachers and administrators (see “What types of challenges do countries/jurisdictions face in addressing curriculum overload, and what strategies do they use to address these challenges?“).

Curriculum imbalance occurs when certain subjects are given priority at the expense of others. More precisely, it refers to disproportionate attention given to certain portions of a curriculum at the expense of others without corresponding adjustments in the conditions or expectations for teaching and learning in those low priority areas. Such imbalance creates a sense of overload in prioritised subjects and a sense of being under-valued or threatened by competition with other subjects. Given that curriculum space is limited, any curriculum choices imply trade-offs.

Some countries/jurisdictions make a distinction between core and non-core subjects. In many OECD countries and partner economies, this usually corresponds to a distinction between academic and non-academic subjects (Table 4). To a lesser extent, some countries/jurisdictions intentionally avoid making the distinction, according the same priority to academic and non-academic subjects, as in British Columbia (Canada), Ontario (Canada) and Québec (Canada), Chile, the Czech Republic, New Zealand, Portugal and Sweden, as well as in partner countries like Argentina, China and India.

Portugal abandoned the distinction between core and non-core subjects in 2016. This distinction had been introduced in 2012 to harmonise curricula on a national level, but teachers and families considered it too restrictive. New Zealand does not use this distinction either, but uses other measures to indicate the relative importance of learning, such as the introduction of national standards for literacy and mathematics.

Such priority subjects are often given a disproportionate amount of instruction time (NCCA, 2010[27]). Such decisions are often driven by the social and political agenda, high-stakes national or state examinations, and/or international assessments.

Over-prioritisation of some subjects may occur by the force of tradition, often for elements considered as “core curriculum” or “the basics” that are historically seen as most important within the school curriculum. It can also occur when the curriculum becomes a means for delivering certain social and political agendas. The United States and European countries sought to strengthen their mathematics and science curriculum as an avenue to boost their international competitiveness (Sahlberg, 2016[101]). Many countries in Africa revised their curriculum to depart from the legacy of colonisation (Majoni, 2017[2]). Similarly, after the fall of Soviet Union, curriculum that had been heavily influenced by ideology was revised to strengthen national elements and develop a standards-based, skill-centred and outcome-oriented curriculum (Moreno, 2007[38]).

When curriculum elements are prioritised or reprioritised without sufficient consideration of what content should be removed or replaced, the curriculum can lose its overall balance (ACARA, 2018[83]; Alexander and Flutter, 2009[4]; Kuiper, Nieveen and Berkvens, 2013[6]; van Silfhout, 2016[102]; Voogt, Nieveen and Klopping, 2017[1]). As school instruction time is limited, other subjects consequently receive less instruction time. For example, subjects such as physical education, arts and music often need to compete for instruction time with so-called “academic subjects” or with core subjects for space in the curriculum.

In Ireland, physical education was once perceived as an underprioritised subject in lower secondary education (MacPhail and Halbert, 2005[103]). This imbalance was addressed and physical education is now part of the core curriculum area of well-being in the Junior Cycle Reform 2015 (Ireland’s reform of ISCED 2). All students must receive 135 hours of physical education spread across the three years. While there is no one-size-fits-all solution that applies across contexts, learning areas and grade levels, some approaches to curriculum content redesign do take into account the need to pre-emptively reduce the threat of content overload.

Over-prioritisation of some subjects and topics can be impacted by policy mechanisms, such as accountability systems and assessments, which signal subject priorities, especially when accountability mechanisms do not coherently link to the curriculum (Jennings and Bearak, 2014[92]). When there is a policy of high-stakes examinations and assessment of student performance (e.g. standardised testing, high school graduation exams, university entrance exams), curriculum may opt to allocate more instruction time to the subjects included in these high-stakes exams.

In England, amidst the focus on high-stakes testing and performance statistics, little or no resources (including instruction time) were allocated to arts and music education, despite the rhetorical commitment of the government of the time to foster creativity (Alexander and Flutter, 2009[4]). Traditionally, literacy and numeracy occupied half of the instruction time in England, while all other subjects had to be squeezed into the remaining half (Alexander, 2009[32]), as cited in (Voogt, Nieveen and Klopping, 2017[1]).

High-stakes examinations play an important role in determining how teachers set their priorities when balancing breadth and depth in curriculum content. Teachers may opt to use a teach-to-the-test approach in the subjects with high-stakes exams, although teachers in various contexts reportedly favour the breadth-of-learning approach, as it provides more curricular coherence and ensures coverage of the knowledge field (Schunk and DiBenedetto, 2016[56]). Teachers overwhelmed by requirements to cover an overloaded curriculum may, in turn, teach to the test, whereby subjects and learning items that are tested receive disproportionately more classroom attention.

Teachers who emphasise fast-paced content coverage may thus curtail in-depth reflection among students and discourage exploration of and engagement with curriculum content (Muijs and Reynolds, 2017[104]). High volumes of content to learn in a limited time may also lead to poor study habits that favour rote learning and memorisation rather than deep understanding, and the broader contexts of support matter for how children can learn and succeed in those contexts (Darling-Hammond et al., 2020[105]).

Furthermore, it has been reported that the teaching-to-the-test mode of instruction undermines teacher autonomy, restricts teachers’ choice of pedagogical practices and limits instructional formats to repetition, rote learning and drill (van der Embse et al., 2017[106]). Teachers restricted to using the transmission model of teaching may experience loss of their agency to make professional decisions, choose pedagogies that work best for their students, foster critical thinking and creative group work, and apply content knowledge to everyday life (Stein, Kintz and Miness, 2016[107]). Narrowing of the role of teachers to fast-paced content delivery may deter potentially good candidates from joining the profession.

Even in countries whose curriculum places student well-being as part of their core values and goals, such high-stakes exams can increase levels of student anxiety and fear of failure (e.g. poor grades, not passing a test), thus negatively impacting their overall sense of life satisfaction. PISA data highlights the prevalence of school-related anxiety among 15-year-old students across OECD countries (Figure 10). This suggests the critical importance of a well-thought alignment between curriculum goals and assessment policies and practices (OECD, Forthcoming[108]).

Globalisation and international competitiveness have been highlighted as major rationales for prioritising literacy and numeracy as they are consistently and reliably measured by international student assessments, such as PISA, the International Association for the Evaluation of Educational Achievement’s Progress in International Reading Literacy Study or its Trends in International Mathematics and Science Study. Recent changes to international assessments like PISA are integrating new innovative domains, such as collaborative problem solving, creative thinking or global competency; which help to expand the common understanding of what matters in learning (OECD, 2020[109]). (See “Local and global citizenship, peace”).

However, international assessments do not always suggest narrowing of the curriculum. In Japan, a 1998 decision to reduce curriculum content had to be reversed to some extent in response to public concerns that schools were lowering the standards in public education. Those concerns were raised in light of the lower-than-expected results of Japanese students in the 2003 PISA study. Other countries/jurisdictions, including Ontario (Canada) (Sahlberg, 2016[101]) and the Netherlands (Kuiper, Nieveen and Berkvens, 2013[6]), opted to increase instructional time for those core subjects to better prepare students for national and international tests. For the same reasons, the 2002-15 No Child Left Behind legislation in the United States prompted most school districts to shift teaching time from social studies, arts and music to reading skills, mathematics and science (Sahlberg, 2016[101]). In analysing the impact of reform efforts on schooling, Pasi Sahlberg (2016[101]) concludes that: “Reading, mathematics and science have now become the main determinants of perceived success or failure of pupils, teachers, and schools in many education systems.”

Regardless of overall curriculum requirements, implementation becomes a factor. Both teachers and students may experience curriculum imbalance and thus overload if the priority for teaching and learning is steered towards giving greater instructional time to some subjects at the expense of others (Lambert, 2001[110]). Thus, it is becoming increasingly important that school leaders and teachers become aware of the issue of curriculum overload themselves and can make informed curriculum decisions and choices as co-designers of an enacted curriculum.

Curriculum redesign occurs on regular intervals. This chapter has covered issues related to curriculum overload that policy makers can keep in mind when redesigning curriculum. Research has examined how overload can occur and suggested strategies and processes for designing curriculum with relevant stakeholders, being responsive to the needs and well-being of students. However, additional research can help illuminate how curriculum overload can be avoided and what components matter especially for students.

In general, there is limited research on curriculum overload. Research focused specifically on students is particularly lacking. Quantitative methodologies that can identify more precise links between curriculum in general and overload in particular are also lacking. Finally, the field can also benefit from additional research in more countries and jurisdictions.

A better understanding of curriculum overload can emerge as new research is conducted. Currently, much remains to be explored. Critical research needs include:

  • Research on this as a key policy issue: Curriculum overload needs to be recognised as a policy research topic in its own right, not merely a consequence of misinformed education policy or a reason for failures in reform implementation. This includes the need to:

    • clarify the links between perceived and actual overload, fine-tune its definition and manifestations and explore in more detail the factors that contribute to it

    • examine the balance between coverage and depth of content that should be covered in curriculum, with more granular analysis of students of various socio-economic backgrounds and differing prior knowledge and skills among other factors

    • accelerate research on political economy of reform with a specific focus on curriculum overload, as curriculum change is politically charged and has trade-offs in terms of policy solutions, with high costs for action or inaction.

  • Studies on student voices, choice and experiences: Most existing research is focused on the perspectives of teachers, administrators and institutions, while the impact of curriculum overload on students remains under-researched (Schmidt and Houang, 2012[33]). There are very few studies documenting students’ views and experiences on the number of topics covered in school. Research is also still scarce on student choice in the specific context of curriculum overload and content reduction is also still scarce (OECD, Forthcoming[111]).

  • Empirical studies involving quantitative methodologies: Most of the available literature draws on qualitative methodologies and self-reporting techniques. While curriculum overload has a strong perceived dimension, impact studies are needed to identify the significance of various contributing factors and the relationships between them. This would make it possible to assess the effects of curriculum overload in the following ways:

    • By identifying the interplay of curriculum overload with related factors. It has been suggested that, instead of considering breadth and depth of a curriculum, attention should be paid to the balance between content and the learning process built into curricula, as well as to quantitative links between instruction time, academic performance, the quality of teaching and the type of student/school (Schwartz et al., 2009[36]).

    • By examining the effects of overload on students (learning outcomes and their well-being, in particular those of disadvantaged students); teachers (teaching practices, self-efficacy and teachers’ well-being); parents (supporting students at home, e.g. homework overload issue, particularly for disadvantaged students), and the interplay among students, teachers and parents.

    • By investigating instructional time as a mediating factor of the effects of overload on students’ learning outcomes, including the organisation of instruction time and its interplay with out-of-classroom activities (out-of-school schedule, sleep, play and socialisation).

    • By documenting curriculum coverage through empirical studies. Systematic school, local, regional and country data about how much of the curriculum is actually covered in schools can be very helpful for gauging levels of curriculum overload in various contexts.

  • In-depth case studies from a greater number of regions and contexts: Available evidence-based literature is often limited to country-specific contexts, such as Australia, England (United Kingdom), Estonia, Ireland, the Netherlands, New Zealand and Singapore. Additional comparative research can identify contextual conditions of curriculum overload and effective solutions across educational contexts (e.g. federal and decentralised governments, tracking and non-tracking, and integrated and differentiated models of instruction).

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Notes

← 1. Note concerning the current and subsequent references to Australian Primary Principals Association (APPA) in this report: The APPA views were written while the Australian Curriculum was being externally reviewed in 2014 and content overload was identified as an issue at that time.

← 2. See Note 1

← 3. See Note 1

← 4. Other compulsory curriculum includes different subjects that cannot be classified within the other groups or which specifically reflect national concerns. The following types of subjects could be included in this category: Latin, ancient Greek, classical studies, minority languages that have not been reported in the Languages 2-5 columns, environmental education, and personal development and well-being (OECD, 2018[113]). An in-depth analysis of other subjects included under “other” compulsory curriculum can be found in OECD subject-specific reports with an exclusive focus on domains like physical education (OECD, 2019[113]).

← 5. See Note 1

← 6. https://www.oecd.org/education/2030-project/contact/Conceptual_learning_framework_Conceptual_papers.pdf

← 7. See (OECD, 2020), Overview brochure of the Education 2030 series of thematic reports on curriculum redesign, OECD Publishing, Paris, https://www.oecd.org/education/2030-project/contact/brochure-thematic-reports-on-curriculum-redesign.pdf

← 8. See Note 1

← 9. See Note 1

← 10. See Note 1

← 11. See Note 1

← 12. See Note 1

← 13. OECD Future of Education and Skills 2030 Curriculum analysis, Progress Report of 9th IWG meeting, [EDU/EDPC(2019)13/ANN1].

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