Keywords

10.1 Introduction

This chapter discusses the empirical chapters of the book. The overall structure of the book, as outlined in Chap. 1 and again shown in Fig. 10.1, organizes the empirical chapters according to the following three approaches:

Fig. 10.1
figure 1

Structure of the book according to the three empirical approaches

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  1. 1.

    Examining the means over time and relations to student achievement in 2019 for content coverage (Chap. 4) and teaching quality and assessment practices (Chap. 5);

  2. 2.

    Explaining changes in achievement over time for content coverage (Chap. 6) and teaching quality and assessment practices (Chap. 7); and

  3. 3.

    Investigating the equality between different groups of students with regard to content coverage (Chap. 8) and teaching quality and assessment practices (Chap. 9).

These approaches align with the main objectives of the book, which are to investigate:

  1. 1.

    how teacher practices have changed over time and their relations with student achievement in IEA’s Trends in International Mathematics and Science Study (TIMSS) 2019,

  2. 2.

    how changes in teacher practices are related to changes in achievement, and

  3. 3.

    how teacher practices are related to educational equality.

Alternatively, the book can be viewed from a more substantive or conceptual perspective, as illustrated in Fig. 10.2. This perspective categorizes the empirical chapters into two areas: (1) content coverage and (2) teaching quality and assessment practices. These two areas are examined from three different perspectives. For instance, in the area of content coverage, the authors examined:

  1. 1.

    how content coverage is related to student achievement in 2019 and how the mean of content coverage has changed over time (Chap. 4);

  2. 2.

    how changes in content coverage are related to the changes in achievement from 2011 to 2019 (Chap. 6), and

  3. 3.

    how content coverage is related to equality (Chap. 8).

Fig. 10.2
figure 2

Structure of the book from a substantive perspective

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In the exact same manner, these three approaches are undertaken to investigate teaching quality and assessment practices (Chaps. 5, 7, and 9).

Choosing whether to summarize and discuss the findings according to the empirical approaches (Fig. 10.1) or substantive perspective (Fig. 10.2) makes a significant difference. Discussing findings based on the three empirical approaches in Fig. 10.1 allows for an examination of the affordances and limitations of each specific approach. For instance, the approach of examining the relation between changes in teaching quality and changes in student achievement over time allows for more robust inferences. However, the constructs have changed over time, leading to reduced validity of the findings. Such discussions are methodologically focused and offer limited insights into the broader field of teacher practice.

On the other hand, summarizing, comparing, and discussing findings from a substantial perspective (Fig. 10.2) enables a more comprehensive exploration of teacher practice from many angles. This approach is valuable for policymakers, practitioners, and researchers. However, comparing findings from chapters that investigate the same concept with different approaches presents challenges. Comparability of findings may be jeopardized due to different operationalizations of the same concepts (e.g., the constructs may have changed over time) and the use of different analytical methods.

To account for the different considerations described above, this chapter starts with brief summaries of the findings from the empirical chapters. It then adopts the substantive perspective (Fig. 10.2) to compare and discuss findings related to content coverage and then teaching quality and assessment practices in light of previous research. Subsequently, the chapter discusses the reliability and validity of findings according to the three empirical approaches, as illustrated in Fig. 10.1. Lastly, the chapter outlines the limitations, contributions, and implications of findings from this book.

10.2 Short Summaries of the Findings of the Chapters

This section provides short summaries of the empirical chapters, following the structure of the book (Fig. 10.1) and the main aims of the book described in the previous section. For more details, please refer to the content of each chapter.

Chapter 4 investigates the alignment between the TIMSS test and the curricula of Nordic countries. It further investigates relations between content coverage and achievement, as well as to what extent the means of content coverage have changed over time. The findings show that there is indeed an alignment between the TIMSS test and the Nordic countries’ curricula. However, few significant relations exist between the content coverage reported by teachers and student achievement. For instance, in 2019, significant positive associations were found between content coverage in geometry and achievement in geometry in Norway, as well as between content coverage in physical science and achievement in physical science in Sweden. Conversely, a negative relationship was found between content coverage in earth science and achievement in both earth science and physical science.

Chapter 5 examines the relationship between teaching quality and assessment practice with achievement using TIMSS data from 2019. It also investigates changes in the means of teaching quality and assessment practice from 2011 to 2019. The findings of the study suggest that classroom management is the strongest predictor of student achievement at the classroom level. Positive relationships were observed between teacher support and instructional clarity with student achievement in mathematics at the classroom level, while in science, these factors were found to be better predictors at the student level. There were no significant findings for cognitive activation, except for inquiry (measured as the frequency of conducting experiments) which had a curve-linear relationship with achievement. Homework frequency was positively related to mathematics achievement in Denmark and Sweden, while the time spent completing homework had a negative relationship with mathematics achievement in Finland. No significant findings were observed for teachers’ assessment strategies. The study also revealed a decrease in teacher support and instructional clarity for all countries, except in Finland, with mixed results for cognitive activation. Homework assignments decreased in all countries, indicating that teachers allocated less homework in 2019 as compared to 2015 and 2011.

Chapter 6 explores the relationship between changes in content coverage and changes in achievement from 2011 to 2019. There were no significant findings for science. For mathematics, there were significant relations between changes in content coverage and changes in achievement for all countries, except for Sweden. Content coverage in topics for the number domain increased over time in all countries and was related to changes in achievement in Norway, Denmark, and Sweden. Content coverage in topics for geometry increased from 2011 to 2019 in Sweden and Finland but decreased in Norway. Changes in content coverage in topics for geometry were only significantly related to changes in achievement in Norway and Finland. Content coverage in topics for data did not change significantly over time in Denmark but decreased in Sweden and Finland and increased in Norway. However, these changes were only significantly related to changes in achievement in Finland and Norway. Due to the large amount of missing data in science, reliable and valid findings were not possible with regards to content coverage in science.

Chapter 7 investigates the relationship between changes in aspects of teaching quality and homework and changes in achievement from 2011 to 2019. Students’ perceived instructional clarity decreased over time in all countries except for Finland. In mathematics, these changes were related to changes in mathematics achievement, while in science, this relation was only significant in Norway. Cognitive activation in science (measured by inquiry practice) decreased in Sweden and increased in Norway but did not change significantly for Sweden or Denmark. Changes in inquiry practice were related to increased achievements in science in Norway and Sweden. In mathematics, cognitive activation increased in Sweden and decreased in Norway, but these changes were not significantly related to changes in mathematics achievement. Limitations to teaching (e.g., students feel tired or hungry, students absent from class) exhibited a negative trend in all countries, indicating that teachers in 2019 reported on more challenges to teaching than in 2011. This negative change was related to changes in achievement over time in all Nordic countries. Homework decreased over time in most countries, but there were hardly any significant relations. Only in Sweden, there was a weak relation between changes in homework and changes in achievement.

Chapter 8 investigates the relationship between content coverage and inequality, specifically by examining whether content coverage mediates the relationship between SES and mathematics achievement. The findings reveal varied results among the Nordic countries. In Denmark, content coverage in the number and geometry topics positively related to SES, with a significant indirect effect in geometry. This indicates that content coverage exacerbates the effect of SES on achievement, thereby reducing equality. In Norway, there was a negative relation between data topics and SES, indicating possible compensatory approaches by schools and increased equality. In Finland, there was no relation between SES and content coverage, and thus no mediation effect occurred. There were no significant effects in Sweden. Furthermore, in Norway and to a certain degree in Sweden, there is a decrease in the amount of content coverage among high-SES students, indicating a compensatory strategy that comes at the expense of students with higher SES backgrounds.

Chapter 9 analyses the relationship between teacher practice and inequality. It further examines whether socioeconomic and ethnic inequalities in students’ mathematics achievement differ significantly across classrooms. The findings reveal two main points. Regarding teacher practice, few significant findings were found, with only Norway exhibiting a relationship between teacher practices and equality. High SES classrooms in Norway reduced inequalities through teachers’ emphasis on academic success and assessment practices. In Denmark, classrooms with a high SES composition were positively associated with teachers’ emphasis on academic success, which in turn, was positively associated with a supportive climate. This was true also for Finland, except that teachers’ emphasis on academic success not only impacted a supportive climate, but also cognitive activation. In Sweden, classrooms with a high SES composition and few minority students, were positively related to teachers’ emphasis on academic success, which in turn, was positively related to a supportive climate and cognitive activation. Furthermore, cognitive activation was positively associated with high content coverage. With regards to socioeconomic and ethnic inequalities, the findings show that classroom socioeconomic and ethnic contexts significantly impact students’ mathematics achievement. Attending classrooms with a high proportion of students with high socioeconomic status was found to have a compensatory effect in reducing the effect of family socioeconomic status on students’ achievement in Norway and Finland. Similarly, attending classrooms with a high proportion of native students was associated with a smaller effect of student ethnicity affecting their achievement in Denmark. No such effects were identified in Sweden.

10.3 Discussion of Findings on Content Coverage

In this section, we discuss the findings on teaching quality and assessment practices by following the substantive perspective illustrated in Fig. 10.2. We focus on three chapters addressing these aspects of teacher practices: Chaps. 4, 6, and 8. We will synthesize the findings from these chapters, compare them across chapters, and relate them to previous research. This section emphasizes the discussion on how content coverage:

  • has changed over time,

  • is related to student achievement,

  • is related to the changes in achievement over time, and

  • is related to educational equality.

Changes in means over time. Chapters 4 and 6 investigate how the means of content coverage in different topics of mathematics and science have changed over time. Both chapters find that there is a larger percentage of students who had teachers who covered the topic number in 2019, compared to 2011. This pattern is consistent across the chapters and across countries. In geometry topics, there was a positive trend for Sweden and Finland, a negative trend for Norway, and no significant findings for Denmark. For data topics, there was a negative trend for Sweden and Finland, a positive trend for Norway, and no significant findings for Denmark. In other words, the only clear pattern identified across countries was that of the positive trend for the topic number. For science, there are no consistent patterns of changes over time in the content coverage of life science, physical science, or earth science across the Nordic countries.

Relations to achievement. Chapters 4, 6, and 8 include investigations of the relations between content coverage and achievement. In Chap. 4, there were few significant findings. In Chap. 6, the data from the three cycles were merged, revealing positive relations between content coverage in all mathematics topics (number, geometry, and data) and student achievement. The relations were small, and significant across all countries except for Sweden. Using data from TIMSS 2019 and controlling for SES, Chap. 8 found positive relations between content coverage in number topics and student achievement in mathematics in all countries except for Sweden. Positive relations were also found for content coverage in geometry and data, but only for Denmark.

Taken together, the findings indicate that: (1) the relations between content coverage and achievement vary across countries, with Sweden being an outlier, and (2) the construct of content coverage has a low statistical power. Only when data from all three cycles are merged, are the relations between content coverage and achievement significant (except for Sweden). This is likely due to the fact that the construct is based on teachers’ responses, and the sample size of teachers is not representative and is also quite small. Another possible explanation is the restriction of time range since within a country in a single cycle, it is rarely expected for teachers to have huge variations in content coverage. The low statistical power could also be due to the low reliability and/or validity of the construct (see Sect. 10.5). Most probably, the reason for the many insignificant findings when using one cycle only is a mix of both. The relation between content coverage and achievement should, according to previous research, be positive and significant (Scheerens, 2016). Indeed, the assumption behind effective learning, is that students’ opportunity to learn the content should have a positive effect on their learning outcome (Scheerens, 2016; Schmidt et al., 2015).

Explaining changes in achievement over time. Chapter 6 investigates the relations between changes in content coverage and changes in achievement. The findings indicate that changes in content coverage in number, geometry, and data, were related to the changes in mathematics achievement. These indirect effects were small, and significant in all countries except for Sweden. Previous research indicates that the changes in students’ opportunity to learn the content will affect their learning outcomes (Scheerens, 2016). Hence, the findings from Sweden are not in line with previous research, and more research is needed to identify the reasons behind this discrepancy.

Relations to educational equality. Chapter 8 investigates how content coverage is related to equality. Of all the Nordic countries, Denmark stands out. In Denmark, high-SES classrooms were to a higher degree exposed to the content in all topics of mathematics. This implies that students in these classrooms were provided with a better opportunity to learn than those in low-SES classrooms. In geometry, there was a significant mediation effect, meaning that the content coverage added to the effect of students’ socioeconomic background. Content coverage in Denmark, hence, increased the gap between low- and high- SES students. In contrast, the opposite was found in Norway. Norwegian students from lower socioeconomic backgrounds were more often exposed to data topics than students from higher SES backgrounds. A similar tendency was found in Sweden for the number topics. These results may point to compensatory approaches by schools and teachers to provide additional opportunities for disadvantaged students.

These findings are partly in line with previous research, which found that content coverage might add to the existing inequalities caused by students’ home background in several countries (Schmidt et al., 2015). Schools may either exacerbate or reduce existing inequalities through students’ opportunities to learn the content of the subject domain.

10.4 Discussion of Findings on Teaching Quality and Assessment Practices

In a similar fashion, as in the previous discussion on content coverage, this section discusses how teaching quality and assessment practices:

  • have changed over time,

  • are related to achievement,

  • are related to changes in achievement over time, and

  • are related to equality.

Changes in means over time. Chapters 5 and 7 investigate whether teaching quality and assessment practices have changed over time, albeit using different methods of analysis. Both chapters find that teacher support and instructional clarity reported by students decreased from 2011 to 2019. This suggests that students perceive their teachers provide less support and less clear and understandable instruction in 2019 than in 2015 and 2011. These results were consistent across countries (except for Finland) and across subject domains (mathematics and science). There were no clear patterns for cognitive activation. Homework assignments decreased over time. The measures for other aspects of teacher practices had changed over time, making it impossible to compare the means of these across the three cycles.

It is challenging to determine why teacher support and clarity decreased over time and whether it was in fact the teaching quality that changed or whether it was students’ perceptions of their teachers that changed. As pointed out in Chap. 5, there are indications that the student composition may have changed, and additionally, teachers reported that there were more challenges or factors limiting their teaching in 2019 as opposed to 2011. Teachers today do indeed face more challenges, as teaching in heterogeneous classrooms where many minority students struggle with language difficulties, is more demanding than teaching homogenous classrooms.

The findings that teachers assigned less homework in 2019 as opposed to 2015 and 2011 raise intriguing questions and open up new areas of investigation. Uncovering the factors driving this trend is not straightforward and calls for further in-depth research.

Relations to achievement. Chapters 5 and 7 explore the relations between teaching quality and assessment practices with student achievements. A pattern of positive relations between teaching quality and achievement is evident across these chapters. However, among the different aspects of teaching quality, classroom management stands out with a strong and consistent relation to achievement. This finding is in line with previous research (e.g., Charalambous & Praetorius, 2020; Senden et al., 2023). Teacher support was found to be positively associated with higher achievement in mathematics, while there were few positive findings in science. There were mostly insignificant findings for cognitive activation, except for inquiry, which is an aspect of cognitive activation in science. The positive relation between inquiry and achievement has been confirmed in previous research (e.g. Teig et al., 2018, 2021, 2022). With the exception of inquiry, cognitive activation seems to be more important in secondary school than in primary school (Nilsen et al., 2018). However, longitudinal data is needed to confirm this.

There were very few significant findings between assessment practices (including homework) and achievement in any of the chapters. Indeed, findings from previous research on this topic are mixed, especially for homework (Fernández-Alonso & Muñiz, 2021). Further research with more nuanced data going deeper into assessment practices and homework is required.

Explaining changes in achievement over time. Chapter 7 investigates whether changes in teaching quality and assessment practices (homework) are related to changes in achievement. There are weak but significant relations between changes in teacher support and changes in student achievement, with the pattern being clearer and stronger in mathematics. Additionally, there was further a pattern of weak but significant relations between changes in inquiry practices and changes in student achievement in science. However, a much stronger and persistent pattern was found for limitations to teaching (e.g., students feel tired or hungry). The findings indicated that limitations to teaching seemed to either hinder further increased achievement for the countries where achievements increased from 2011 to 2019 or explain decreased achievements for the countries with negative trends in achievement during the same period. For Norway, this finding is aligned with previous research on students in grade nine (e.g. Kaarstein & Nilsen, 2021; Nilsen et al., 2022; Vik et al., 2022). However, further research is needed in the other Nordic countries to confirm this finding, preferably with longitudinal data.

When examining teachers’ assessment practices, there were no significant patterns or consistent relationships. This means that the chapter did not find a clear link or correlation between the changes in achievement and the changes in assessment practices that focus on homework frequency, homework time, and in-class homework discussion.

Relations to educational equality. Chapter 9 investigates the relations between teacher practice and educational inequalities. The findings suggest that in all Nordic countries, except Norway, teacher practices neither reduce nor increase the relation between SES and achievement. However, in Norway, being a minority student had less impact on achievement in high SES classrooms than low SES classroom. According to previous research, teaching quality has the potential to reduce or increase inequalities in learning outcomes caused by SES (Cardichon et al., 2020; Nilsen et al., 2020; Rjosk et al., 2014). Hence, the insignificant findings for the other Nordic countries are to some degree unexpected. The few significant findings could be related to the complexity of the statistical model used. This model includes a large number of variables, and it includes classroom SES, which is a powerful predictor. In this chapter, classroom SES and minority background are the main moderators of the relations between individual SES (and minority) on achievement, mediated via teacher practices, school emphasis on success (SEAS), and opportunities to learn (OTL). In other words, the authors examine whether classroom SES and minority may reduce achievement gaps between individual students (via teacher practices, SEAS, and OTL). If the research question rather focused on teacher practices as the moderator of the relations between individual SES (and minority) on achievement (controlled for SEAS and OTL), this could have provided more information on whether teacher practices may reduce inequalities.

Chapter 9 also includes findings on relations between classroom composition and teacher practice. Apart from Norway, high SES classrooms were positively associated with high values of teachers’ emphasis on academic success which in turn was positively associated with higher teaching quality in the other Nordic countries. This could indicate unequal distribution of high-quality teachers, in that high-quality teachers tend to teach high SES schools. This is in line with previous research (Cardichon et al., 2020; Nilsen & Bergem, 2020; Qin & Bowen, 2019), and an indication of inequality in access to good teachers.

10.5 Reliability and Validity

In our discussions about the reliability and validity of findings, we follow the structure of the book, as illustrated in Fig. 10.1. This means that the discussions are structured according to the three empirical approaches used in the book:

  • Approach 1: analyses of relations between teacher practices and student achievement in 2019, including estimations of means of teachers practices across the three cycles of TIMSS.

  • Approach 2: analyses of relations between changes of teachers practices with changes in achievement from 2011 to 2019.

  • Approach 3: analyses of the interplay between teacher practices and educational inequality.

10.5.1 Approach 1: Relations to Achievement in 2019

Chapters 4 and 5 both utilized two-level structural equation modelling at the students and classroom levels to investigate relations between teacher practice and student achievement in 2019. This analytical method allows for simultaneous estimations at both levels and provides model fits (Hox & Roberts, 2011). Structural equation modelling, using the software Mplus, further provides the reliability and validity of the constructs through confirmatory factor analyses, yielding robust findings (Morin et al., 2014).

In 2019, the validity of teaching quality was high (Klieme & Nilsen, 2022). This can be attributed to several factors. The measures for teaching quality in TIMSS are heavily based on theory and previous research (Baumert et al., 2010; Klieme et al., 2009; Mullis & Martin, 2017). Since 1995, TIMSS has already included aspects of teaching quality (Klieme & Nilsen, 2022). Building on this foundation, a broader and more comprehensive measure of teaching quality was introduced in TIMSS 2015 and has been piloted, tested, and improved several times.

The reliability and validity of content coverage, on the other hand, are more problematic. This is first and foremost related to the response scale. Teachers are asked when the students in the class were taught various topics within the domains of geometry, number, and data in the subject of mathematics. Similarly, they are asked about all the topics within the domain’s life science, physical science, and earth science in the subject of science. The response scale consists of three categories: mostly taught before this year, mostly taught this year, and not yet taught or just introduced.

The problem with the response scale lies primarily in the response option “not yet taught or just introduced”, as this could be interpreted to include two different responses (not yet taught/just introduced). This ambiguity may be the reason why higher values of the response scale are not necessarily associated with higher achievement, as illustrated in Fig. 10.3. In this figure, “mostly taught before this year” corresponds to higher achievement than “not yet taught or just introduced”. This makes sense, however, one would expect “mostly taught this year” to correspond to the highest achievement compared to other responses. In TIMSS 2023, this issue has been addressed.

Fig. 10.3
figure 3

The graph association between teachers’ response on a topic in the domain geometry and the first plausible value of mathematics achievement

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Another factor contributing to the low validity of content coverage is the large number of missing data, especially in science. The exact reasons for the high number of missing values are not clear, but it is possible that survey fatigue played a role, as the questions about science topics come after those about mathematics topics. Additionally, there are numerous items for the teachers to complete, which could also contribute to missing data due to fatigue. These issues may have contributed to the small number of significant findings in the chapters examining content coverage, along with the small and not representative sample of teachers.

10.5.2 Approach 2: Explaining Changes in Achievement

Approach 2 is the analyses of the relations between changes in teachers’ practice and changes in achievements and are employed in Chaps. 6 and 7. The method of analyses used in these two chapters is robust and increases the plausibility of causal inferences. In this respect, the inferences should be reliable and valid. However, several of the constructs have changed over time, which may reduce the reliability and validity of some results. For instance, the aspect of teaching quality referred to as cognitive activation has changed from 2011 to 2019. The following six items were included in both cycles 2019 and 2015, but not in 2011: ask students to explain their answers; ask students to complete challenging exercises that require them to go beyond the instruction; encourage classroom discussions among students; link new content to students’ prior knowledge; ask students to decide their own problem-solving procedures; and encourage students to express their ideas in class. For cognitive activation in mathematics, only two items remained unchanged from 2011 to 2019, reducing the validity of the construct.

Regarding content coverage, there were few changes over time (for more on this, see Chap. 6). However, the large amount of missing data in science (except for Finland) across several cycles prevented reliable and valid findings concerning content coverage in science.

10.5.3 Approach 3: Equality

Approach 3 involves analyses designed to disentangle the interplay between teacher practice and educational equality. Chapters 8 and 9 investigate this for content coverage and teacher practices, respectively. However, the two chapters use different approaches.

Chapter 8 uses an additive approach, where content coverage mediates the relation between SES and achievement. This approach is referred to as additive because it investigates whether a mediator (in this case, content coverage) may add to the effect of the predictor (here, SES). This approach is in accordance with previous theories on opportunities to learn and equality (e.g. Schmidt et al., 2015).

On the other hand, Chap. 9 uses a differential approach and investigates whether teacher practice moderates the relation between SES and achievement (or the effect of ethnicity on achievement). This approach is used to investigate whether a moderator (in this case, teacher practice) may reduce or increase (i.e., moderate) the strength of the effect of SES on achievement. This approach is in accordance with previous research (e.g. Gustafsson et al., 2018; Nilsen et al., 2020), as one may expect, different aspects of teacher practice have varying effects on different groups of students (hence the term differential effect). However, in Chap. 9, this moderation is just part of a larger model that investigates whether attending a school or classroom with high SES reduces or increases the importance of students’ individual home background via teacher practice.

While both chapters use robust and advanced methodology, they report few significant findings, which is partly contradictory to previous research. The limited significant findings in Chap. 8 may be due to the low validity of the content coverage construct, while the few significant findings in Chap. 9 might be attributed to the complex model incorporating a large number of variables and relationships.

10.6 Contributions and Concluding Remarks

The main aim of this book was to investigate teacher practices in grade four from multiple perspectives: how they are related to achievement, how they have changed over time and whether these changes are related to the changes in achievement, and how they are related to equality. The summaries of the findings from all the empirical chapters and the discussions of these findings across chapter and in light of previous research has revealed:

  1. (1)

    The findings are mostly in line with previous research.

  2. (2)

    Teaching quality is crucial to student achievement. In primary school (grades four and five), the results indicate that classroom management in mathematics, inquiry practices in science, as well as teacher support and instructional clarity in both subjects are associated with higher learning outcomes.

  3. (3)

    Students’ opportunity to learn the content in mathematics (content coverage) is essential to student achievement; however, results vary across countries and content domains (number, geometry, and data)

  4. (4)

    Teachers in Nordic countries have reduced the amount of homework they assign to students over time, and findings on homework are mixed. More research is needed with data providing more in-depth information, including the type of homework assigned to the students (e.g., focus on skill development or content reinforcement), and how these different types may affect student outcomes.

  5. (5)

    Students in high SES classrooms or schools are provided with better opportunities to learn the content (especially in Denmark) and experience higher teaching quality. However, in Norway, teaching quality compensates the gap between disadvantaged and advantaged students.

  6. (6)

    Teachers are facing growing challenges in their teaching due to the heterogeneity of their classrooms and students who may not have had sufficient sleep or nutrition. These challenges to teaching may explain the decreased achievement observed or hinder further increases in achievement since 2011.

This book contributes to educational policy and points to the need for more equal opportunities for students to learn. It is problematic that high SES schools tend to get the best teachers, as this exacerbates existing inequalities caused by students’ home backgrounds and minority status. This contradicts the Nordic model of education (see Chap. 1). In our times of growing inequalities caused by the COVID-19 pandemic, war, climate and energy crises, the inequalities in society, spread and influence schools as well. It is therefore important to decrease inequalities in society and equip teachers to teach in heterogeneous classrooms. A substantial body of research has shown that equality promotes quality in school and prosperous societies (Hanushek & Woessmann, 2015; Wilkinson & Pickett, 2011).

This book also contributes to teacher education and the research in the fields of teaching quality and teacher effectiveness. Most research on teacher practices comes from the USA or Germany, and research on teaching quality in mathematics and science more often involves students in secondary school rather than students in grade four or grade five. Our research adds to this previous research by including the Nordic context and younger students.

In terms of methodology, our book has the advantage of using the same concepts and operationalizations, methodological approaches, and the same samples and data (see Chap. 3). This allows for comparisons of findings across chapters and facilitates a deeper understanding of the relationships between variables. The methods of analysis employed in the various chapters have been carefully chosen to ensure robust, reliable, and valid inferences, which are essential for the credibility and impact of the research findings. Moreover, the method used to examine the relations between changes in teacher practice and changes in achievement could prove beneficial for other countries as well, as it provides a replicable and adaptable framework for analyzing similar phenomena in different contexts.

A mantra followed since 1995 in TIMSS is: if you want to measure change, don’t change the measure (Martin et al., 2020). It is indeed important to follow this, as evidenced by the challenges faced by the chapters that investigated changes in teacher practice in relation to changes in achievement (Chaps. 6 and 7). For the most part, TIMSS does indeed follow this rule. However, there needs to be a balance between maintaining trend measures and the need to improve and align with changes by the societies and schools of the participating countries. In the case of teaching quality, the change has improved the quality of the measures and enabled research of this important concept (Klieme & Nilsen, 2022).

The classroom design of TIMSS is particularly valuable for examining the role of teacher practice in relation to students’ learning outcomes and educational equality. By sampling intact classes from schools, and collecting representative data from students, their teachers, and parents through questionnaires, TIMSS offers a comprehensive and unique perspective on the educational landscape. This approach sets TIMSS apart from other international large-scale studies, such as the Teaching and Learning International Survey (TALIS) and the Programme for International Student Assessment (PISA). TALIS does not measure student learning outcomes, while PISA does not sample whole classes, include teacher questionnaires for the teachers of the sampled students, or involve primary school students.

The wealth of data provided by TIMSS has enabled us to draw meaningful comparisons about effective and equitable teacher practice across the Nordic countries. By sharing insights and best practices, these countries can work towards a more unified and effective Nordic education system, while reducing disparities and inequalities that have emerged over time. Hopefully, our book contributes to this ongoing dialogue and takes us one step closer to achieving the Nordic model’s aim of greater educational equity and excellence.