Enhancing non-cognitive skills by applying lesson study in lower secondary education: A project in Vietnam

Abstract This study examined the quantitative relationship between lesson study and non-cognitive skills in Vietnam, using t-test analysis for comparison before and after. We also looked at the relationship between lesson study and cognitive skills, teacher engagement and parental involvement. Unlike former studies, we found no relationship between lesson study and cognitive skills, however that is consistent with the general finding in the literature that lesson study seems to have more of an impact on academic performance at the primary than at the secondary level. Nonetheless, and most importantly, we did find a statistically significant relationship between lesson study and non-cognitive skills, specifically extraversion and conscientiousness, two of the Big Five traits that psychologists generally agree make up the taxonomy of non-cognitive traits. We also found that lesson study led teachers to have more dialogue with their students and parents to engage more with their children on their academic progress. In light of the correlation between lower secondary education and non-cognitive skills, these results suggest that lesson study at the lower secondary level may lead to improved academic outcomes at the upper secondary and higher education levels as well as improved life outcomes including behavioral and labor market outcomes.


PUBLIC INTEREST STATEMENT
The Lesson Study method initiated in Japan has been a particular interest of Hiroshima University's Center for International Cooperation in Education. Lesson study has in recent decades spread to many countries, including Vietnam, in an attempt to improve both teaching quality and student performance on cognitive skills, typically in specific subject areas. A relatively neglected aspect of lesson study, however, is its impact also on students' non-cognitive skills and on students' interactions with their teachers and parents. This research on a small sample and on a small number of non-cognitive skills suggests that such impacts do indeed occur in rural Vietnam, and paves the way for broader research into causation and into the relationship between lesson study and other non-cognitive skills.

Introduction
Jugyou kenkyuu (lesson study) has been established for over a hundred years in Japan for teacher professional development, initially at the primary level and slightly later at the lower secondary level (Arani et al., 2010). Lesson study professional development involves both collaborative teacher learning and individual teacher development (Perry & Lewis, 2009), pedagogical skills (Cerbin & Kopp, 2006) and pedagogical reform (Saito & Atencio, 2013). The major steps are a. collaboratively planning the study lesson; b. implementing the study lesson; c. discussing the study lesson; d. revising the lesson plan (optional); e. teaching the revised version of the lesson (optional); and f. sharing thoughts about the revised version (Fernandez & Yoshida, 2004).
The lesson study provided by teachers in Japan has been more successful at the primary school level than at the secondary level for several reasons. The main reason is that secondary school involves specialized subjects with different teachers for each subject and the teachers believe that they can share among themselves the main points of lesson study, in terms of both teaching materials and techniques, rather than practicing lesson study with the participation of all the teachers in a school (Tsukui & Murase, 2019). Practicing lesson study has strengthened the teaching of mathematics via three pathways to instructional improvement: teachers' knowledge, teachers' commitment and community, and learning resources such as books and materials (Lewis et al., 2006). Stigler and Hiebert (1999) also noted that a substantial goal of lesson study is to improve students' learning achievement, stimulating their interest in mathematics and developing their ability to add unlike fractions (those with different denominators).
Since the 1990s, lesson study has also influenced western countries such as the US, the UK and Australia. In the US, when teachers use high-quality curricula, school-based lesson study using Japanese teacher manuals has significantly developed teachers' knowledge and thus led to improved student mathematics learning outcomes (C. C. Lewis et al., 2012). Similarly, in the UK, lesson study has successfully improved professional knowledge and practice among primary school teachers and school leaders in both math and English (Dudley, 2012). Groves et al. (2013) implemented lesson study for both mathematics lessons and professional learning in Australia. As in Japan, lesson study in Australia requires genuine teacher-researcher collaboration and the involvement of specific outside experts, including typically educational consultants, district personnel, and university educators.
Globally, lesson study has been shown to develop higher student academic performance in mathematics (Alamri, 2020;Bruce et al., 2016;Dudley et al., 2019;Lewis & Perry, 2017), English language learning (Kıncal et al., 2019) and reading comprehension (Özdemir, 2019), as well as learning among students from disadvantaged groups (Churches, 2016). The impact of lesson study on student academic outcomes is mainly measured in three ways: a. testing before and after lesson study; b. interviewing students and teachers about positive changes-and in some cases tracking these over time; and c. more recently, conducting large scale randomized control trials (Churches, 2016).
Lesson study first influenced Anglophone countries, as noted above, but has subsequently spread also to several Asian countries, notably China, South Korea, Taiwan, Indonesia, Vietnam, Hong Kong, Singapore and Thailand. In Asia, especially after the Asian economic crisis of the late 1990s, lesson study has focused on broader educational issues, including family problems, dropout, and delinquency among children. Indeed the Asian economic crisis has led to lesson study moving to pay attention to school reforms that improve children's well-being and learning (Saito et al., 2015). Japan also has experienced a drastic change as a result of this, with positive results such as reduced dropout, more attention to learning, and remarkable increases in test scores (Tsukui & Murase, 2019).
Previous lesson study research has only looked at teachers' knowledge development or at students' academic performance as reflected in cognitive skills, even though children's wellbeing also depends very significantly on children's non-cognitive skills. Much of the previous research has not been sufficiently rigorous for its results to be certain, however. Nonetheless, according to key literature reviews of studies published from 2000-2010 (Cheung & Wong, (2014).4) and from 2010-2018 (Willems & Bossche, (2019).), the very small number of rigorous studies have indicated a clear relationship between lesson study and both teacher development and student academic performance. Lesson study has also proved effective in improving the way teachers handle students with special needs (Leifler, 2020). More studies are necessary, however, using more rigorous evaluation techniques such as randomized control trials and blinding.
Globally, non-cognitive skills have been shown to have behavioral outcomes in both school and the workplace, as demonstrated by studies in psychology, education, and behavioral economics. Gutman and Schoon (2013) argued that non-cognitive skills are more important for young people than cognitive skills-as non-cognitive skills create the attitudes, behaviors, and strategies that are in high demand in school and the workplace, including motivation, perseverance, and self-control. Indeed, there are numerous studies investigating non-cognitive skills and students' academic outcomes, as well as their future life outcomes, especially in economics, psychology and education. Very interestingly, there are some studies in the US that suggest that, for adolescents, teachers have more of an impact on non-cognitive than on cognitive skills (Jackson, 2012; Tough, 2013) but this was not found in the Young Lives study of the lasting effect of teachers in Ethiopia and Vietnam (Crawfurd & Rolleston, 2020).
The well-known evidence from the High Scope Perry preschool program in the United States found that non-cognitive skills are formed mainly in early childhood, and that childhood differences in non-cognitive skills persist into adulthood and determine future socio-economic status (J. Heckman et al., 2010). Student non-cognitive skills are also more important than cognitive skills in determining adolescent academic outcomes, behavioral outcomes and labor market outcomes (J. J. Heckman et al., 2006). More recent research synthesis also involving Heckman has also shown (a) that non-cognitive skills are important both for academic achievement and for life outcomes beyond just education; and (b) that though the early years are the most important, nonetheless non-cognitive skills can change later on as a result of parents, schools and social environments (Kautz, Heckman, et al., 2014).
Psychologists have developed taxonomies for non-cognitive skills, of which the most common taxonomy focuses on the Big Five traits known as OCEAN: Openness to Experience, Conscientiousness, Extraversion, Agreeableness and Neuroticism/Emotional Stability (Costa & McCrae, 1992). In this study, data were available for two of the five: Conscientiousness and Extraversion. The American Psychological Association Dictionary defines Conscientiousness as "the tendency to be organized, responsible and hardworking" and Extraversion as "an orientation of one's interests and energies toward the outer world of people rather than the inner world of subjective experience" (Kautz, Heckman, et al., 2014, p. 15).
At the time the data for our study were collected (2017-18), Vietnam had a total population of 92 million, of whom 22 million were aged under 15. It had achieved significant improvements in education in terms of both access and quality since its 1986 educational reforms, surprising the world with its first participation in 2012 in the PISA international assessment of education where it scored higher than the OECD average (Patrinos et al., 2018). Indeed, Vietnam now ranks 27 th out of 157 countries on the World Bank harmonized learning outcomes scale. Almost all children were enrolled in primary school and in lower secondary school, and learning levels had been rising. However, upper secondary school still only enrolled 63% of the relevant age group (the exclusion of low-income students from upper secondary school may account for the PISA results as PISA is a school population assessment, not a total population one). The government spent 15% of its budget on education, equivalent to 4.2% of GDP (IBRD-IDA, 2022;Patrinos et al., 2018) Despite significant increases in enrolments (from 69% in 2000 to 92% in 2012, for example), the lower secondary level in Vietnam still faces access and quality challenges, especially in rural areas. These challenges make it difficult for over a third of Vietnamese to go on to upper secondary and even fewer go on to higher education, even though the rural-urban education gap has begun to decline. Moreover, Yarema (2010) describes how lesson study could promote explicit student understanding of lessons' content structures, leading not only to students' academic achievement but also to students' non-cognitive skill development. However, there is no existing study that examines students' non-cognitive skill development as a result of lesson study activity. Accordingly, this study focused on the use of lesson study in lower secondary education of Vietnam as quality assurance for the non-cognitive skills that strongly influence academic performance.
The organization of this paper is as follows. Section 2 reviews the literature of lesson study and students' non-cognitive skills in Vietnam; Section 3 summarizes our data from a questionnaire completed by lower secondary students; Section 4 describes our methodology and research methods; Section 5 presents and discusses our analysis of the correlation between lesson study and students' non-cognitive skills; and, finally, Section 6 contains our conclusions.

Lesson study in Vietnam
Since its education reform, Vietnam has been concerned that students must be capable of active critical thinking and self-learning rather than rote memorization and passive learning, meaning that improvements were needed in their questioning, evaluating, generalizing, debating and analyzing skills (Hong Thanh, 2011). This required teachers to have the skills to promote studentcentered learning (for instance, engaging in thinking, active participation and problem-solving) as well as implementing a national curriculum reform. As part of this attempt to improve teachers' pedagogical skills, lesson study from Japan was introduced and applied in Vietnamese schools. Initially, the Japanese International Cooperation Agency introduced guidelines to strengthen teaching skills, especially in mathematics and science subjects (Saito, 2012). Subsequently, Japanese lesson study has been frequently adopted in both primary and secondary schools. Lewis et al. (2019) noted the four stages of lesson study: Study, Plan, Teach, and Reflect. Study involves linking teaching and long-term objectives in the light of research and joint studying. Plan is when teachers prepare by learning deeper subject knowledge and including ideas from students and colleagues. Teach is when they deliver the lesson and see what students learn and experience from it. Reflect is when the teachers consider feedback and their own reactions, leading to further revisions for next time.
There are several analyses of lesson study in Vietnam. Vui (2007) examined the implementation of lesson study to develop students' mathematical thinking by solving problems and equipping primary students with basic mathematical skills using videotaped lessons by senior teachers. There was some progress in developing students' mathematical thinking, but teachers still needed practical lesson frameworks and deeper understanding and longer training in the lesson study process. Saito et al. (2008) focused on lesson study problems among primary school teachers in Bac Giang province, where lesson study was conducted by a collaboration between the Vietnamese and Japanese governments on an in-service teacher-training program. Saito et al.
found that teachers 1) deliver lesson study sessions very fast, 2) lack teaching skills, and 3) do not have any dialog with colleagues to discuss and share about teaching methods. Vui (2014) described a small application of lesson study in mathematics education in one secondary school in Vietnam. Lesson study resulted in innovations in teaching methods, improved student learning, improved teacher professional development, and innovations in applying a new curriculum. In particular, students achieved a better grasp of mathematical concepts by having to come up with solutions to open-ended questions based on real-life situations.
Interestingly, Van Thang (2018) implemented applying lesson study for both students and teachers. Students were trained how to teach other students, so that they could acquire academic knowledge through a teaching mechanism, even though lesson study is normally delivered by school teachers. Teachers provided lesson study plans and practice methods to the students, observed the students teaching, and then discussed with them their reflections about their teaching. Through this type of indirect lesson study carried out by students, teachers could improve actual teaching skills, adjusting their own lessons in the light of students' actual knowledge levels and achievements.
Although lesson study has been applied in several ways to develop teaching and learning skills in Vietnam, there are few analyses of it. Such studies as do exist seem to show similar positive effects on both teachers' teaching development and students' learning development, as do many analyses of lesson study in other countries. Most analyses in Vietnam (Bruce et al., 2016;Chong et al., 2017;Duc & Chien, 2014;Kieu, 2018;Lewis & Perry, 2017;Vui, 2014) have focused on student cognitive skills in subjects like mathematics and science, including an interesting recent paper that combines lesson study with the micro lesson method for young chemistry teachers in northern Vietnam (Huong et al., 2021).
Prior studies in Vietnam have thus not focused on student non-cognitive skills through lesson study as we do. As have previous studies, we also include student cognitive skills and teacher development, but for a wider range of subjects than have most other studies. Little and Azubuike (2017) investigated the associations between non-cognitive skills and academic outcomes using exploratory factor analysis in urban and rural areas of Ethiopia, India and Vietnam. In Vietnam, non-cognitive skills were correlated with personal development, academic beliefs such as self-efficacy, and positive self-concept (view of oneself) and assessment domination (when more interested in test scores than in the subject itself) in math and English. Van Huynh (2019) suggested that social emotional learning, which is part of the non-cognitive domain, should be embedded in Vietnamese primary classrooms because social emotional skills can help to solve problematic situations involving students, as well as for many other reasons. Hoang and Vu (2016) have also emphasized the importance of teaching social and emotional skills to students and explored its challenges and opportunities in Vietnamese middle schools. Social emotional learning had benefits for students in terms of sharing thoughts, expressing feelings and having sympathy with peers. However, there were some challenges, including the frequency of regular learning practice sessions, difficulties understanding various new concepts in learning and training, and the sustainability of family commitments to their children's education. An empirical study by Espinosa (2017) indicated that educational inputs influenced cognitive and non-cognitive skills in terms of self-esteem and selfefficacy. The non-cognitive skills were developed by peer relationships and also by the children's relationship to their parents and their provision of academic support. The findings recommended Vietnamese education policies need to incorporate non-cognitive development, with its assessment linked to school accountability. However, Huynh et al. (2021) listed four social-emotional learning challenges in Vietnamese secondary education: the disconnect between the curriculum and teachers' ability to teach; the perception that it is difficult to integrate social-emotional learning into education; insufficient attention to student psychology; and students' inability to develop social-emotional competence.

Students' non-cognitive skills in Vietnam
The most relevant analysis for this paper  examined the association between grade 10 students' non-cognitive skills (learning motivation and self-concept) and learning outcomes in both mathematics and English language, also comparing genders (though they did not look at lesson study). The students' self-concept is influenced by their judgment regarding classroom peer relationships. The findings showed that boys had higher levels of self-concept but less motivation to learn than did girls, and that girls' higher motivation to learn meant that they had higher academic scores, a finding consistent with many upper and middle-income countries.

Data
As many analyses indicated that non-cognitive skills are strongly correlated with academic achievement and that the Japanese lesson study method was helping to strengthen teacher development and students' academic performance, our study focused on students' noncognitive skills development through lesson study in the Nguyen Truc junior high school in the Thanh Oai district of Vietnam. The Thanh Oai district is one of several economically emerging cities near Hanoi City, with new manufacturing and transportation businesses, although it is still surrounded by mainly agricultural areas. This economic development led to a significant increase in awareness about the importance of education investment to promote education quality in Thanh Oai as much of the district's economic growth is effectively related to increased education levels.
Moreover, since 2010, Vietnam has held teaching competitions throughout the country among teachers at school, province, prefecture and city levels, designed to improve teaching skills and hence education quality and also to shift teaching away from one-sided lecturing towards interactive learning. Many of the teachers taking part in the competitions have adopted the lesson study process, including several teachers from the Nguyen Truc junior high school who have won various competitions, despite the school as a whole struggling with low skilled teachers and continued rote learning. Supported by the principal, the several teachers who won the competitions were extremely keen to use the lesson study process more in their classes and introduce lesson study throughout the school. They were supported in doing this by cooperative arrangements with the Center for the Study of International Cooperation in Education (CICE) at Hiroshima University in Japan and the Vietnam National University in Hanoi. Teacher development was seen as the main purpose of introducing more lesson study processes.
A survey of 72 grade 8 students was conducted by CICE to examine differences before and after lesson study in 2017-2018 (that only lasted for two months). The survey used a questionnaire that included cognitive assessments in each subject (mathematics, literature, English, biology, chemistry, physics, and history) together with non-cognitive assessments of extraversion and conscientiousness traits. Note the wide range of subjects covered, very different from most previous analyses of lesson study that have typically been confined to only one subject. The test of extraversion examined the student's relationship with the teacher to estimate the student's communication skills and learning motivation. The non-cognitive trait of conscientiousness was evaluated by examining how much time students spent studying on their own outside the classroom. The survey also examined teacher development as the principal purpose of the typical lesson study, as assessed by teachers' commitment and involvement with students both inside and outside the classroom.
The main contents of the questionnaire completed by the students were 1) test scores, 2) relationship with the teacher, 3) student study effort, 4) the teacher's understanding of the student's comprehension, 5) and 6) the teacher's engagement with the student inside and outside the classroom, and 7) parental involvement (see the Appendix). Figures 1-7 provide an overview of the data obtained, including average values for the indicators of students' cognitive and non-cognitive skill development as well as of teachers' pedagogical development, before and after lesson study.
To organize the data, we first summarized the students' responses about themselves in Figures 1-3. Figure 1 shows their academic performance before and after lesson study in terms of cognitive skills in seven subjects. The data reported in the questionnaire show (a) very high scores on all subjects except Literature even before lesson study; and (b) no major improvements in cognitive skills as a result of lesson study. While there was a minor improvement in Biology, History, Math, Physics and Literature, there was also a minor decline in both Chemistry and English (Statistical analysis of the results is presented in section 4. 1).
The most important data used in this study are presented in Figures 2 and 3, that provide indicators of the non-cognitive trait of conscientiousness. Figure 2 explains the students' closeness  to their class teacher for each subject. The data show that this closeness greatly increased in all subjects after lesson study, though this was very minor for Physics. Note that this is not yet an analytical result but a presentation of the data. Figure 3 describes how the students' behavior changed in terms of their effort, measured by the hours per week they spent studying for each subject. Study time increased moderately for most subjects after lesson study, though not for Literature or Physics.
After organizing the data about students in Figures 1-3, we then organized the data about teachers in Figures 4-6 to prepare to investigate teachers' skill development as a result of lesson study. Figure 4 reports the extent that teachers notice how much students understand lesson contents for each subject. Except for Physics, the teachers' understanding of students' comprehension increased considerably after lesson study in almost every subject, and especially in Math and Chemistry.
Similar to Figures 4-6 report data on teacher skill development in terms of teachers' interactive communication with students, inside and outside the classroom. This was very noticeable inside the classroom in all subjects except Physics and outside the classroom for all subjects, though least so for Physics and Literature. Generally, the results for Physics and Literature in Figures 1-6 are not as good as those for other subjects. This possibly implies less interest in lesson study by the teachers of those two subjects.
Finally, we organized the questionnaire responses about parents' attitudes to support their children's education. This included such things as providing advice, checking homework and test results, and communicating with their children and the school teachers and principal. The data are summarized in Figure 7. Lesson study improved parental involvement with respect to all these dimensions.

Methodology
Several studies (e.g., Angeles & Matsuura, 2019;Fadillah et al., 2017) have used the t-test to analyze the quantitative relationship between lesson study and students' academic performance and between lesson study and teacher development-and we continue this analysis. However, until our study, no quantitative analysis had been conducted into the relationship between lesson study and students' non-cognitive skills. In sum, therefore, we employed the t-test statistical method to understand the overall relationships between lesson study and students' cognitive skills, between lesson study and students' non-cognitive skills and between lesson study and teacher development, using a before and after lesson study comparison of the indicators of the average values shown above in Figures 1-7. Specifically, using the paired t-test method, we conducted a t-test to determine whether or not there was an improvement in the index of each questionnaire item by focusing on the difference (d: difference) between the mean value of each questionnaire item for the same group of students before and after their teachers took the lesson study.
The paired t-test method can be written as follows: where H 0 means that there were no indicators improved by lesson study and H 1 means that some indicators were improved by lesson study.
The test for these hypotheses is given by the following test statistics where � d is the mean of the differences between before and after for each item, and s d is the sample standard deviation of those differences. Moreover μ is the mean of the population, so if H 0 is correct, μ ¼ 0, and we can rewrite Equation 1) as follows: We also estimated whether or not lesson study had an effect on the improvement of each item by conducting a one tailed t-test. Table 1 employs the t-test method to examine the students' academic performance on their yearend examination score to show student's cognitive skills in 7 academic subjects after lesson study. A significant change appeared only in History, statistically at the 10% significance level; other subjects showed no significant differences, and the mean values in English and in Chemistry even decreased after lesson study. We double-checked this result using one-tailed and two tailed tests.

Students' cognitive skills
With both there is no statistical significance, so it is difficult to say if the students' cognitive skills decreased or increased through lesson study. This finding is that lesson study did not improve students' academic performance in Vietnam. This result is different from many previous studies that showed higher academic performance in mathematics, English, language learning and reading comprehension (Alamri, 2020;Bruce et al., 2016;Dudley et al., 2019;Lewis & Perry, 2017;Özdemir, 2019). However, this is probably because students' test scores in our sample were already relatively high before lesson study (see, Figure 1) and therefore grade 8 students would have found it difficult to improve their exam scores quickly or easily during the short-term lesson study project (that only lasted for two months). Lesson study may not have any very short-term impact on students' academic performance in lower secondary school, especially when students are already performing well, considering also that Arani et al. (2010) have argued that lesson study functions best in the lower grades of primary school.

Students' non-cognitive skills
Tables 2 and 3 report estimates of students' non-cognitive traits in extraversion and conscientiousness in terms of building a good relationship with the teacher and of spontaneous learning motivation as indicated by increased study time after the lesson study. Table 2 presents how good was the relationship between students and teachers for all seven subjects, reflecting a 5-point scale within the questionnaire (see Appendix). There is a statistically significant improvement in the relationship between students and teachers in all subjects except Literature and Physics (though the sample size for Chemistry was much lower than for all other subjects). Table 3 demonstrates students' non-cognitive skills development as indicated by increasing their study hours by themselves. The increased study hour intervals in the survey were: 1. zero, 2. 0.5-1 hour, 3. 1-1.5 hours, 4. 1.5-2 hours, and 5. more than 2 hours. Most students studied for a longer time than before lesson study. However, this result is statistically significant for Mathematics, English, Biology and Chemistry but not for other subjects. This result is similar to the other non-cognitive skill test in Table 2 that showed the relationship with the teacher for each subject.  ***, ** and * indicate significance at 1%, 5% and 10% levels.
Our first major new finding is thus that lesson study is an important factor for student noncognitive skill development, and not only for teacher development as most previous literature has investigated. Lesson study has the capacity to improve student non-cognitive skills (related to 21 st century skills as strongly stressed by Gutman and Schoon (2013)). This is very important and implies that lesson study may increasingly be an important factor not only for academic outcomes but also for future employment outcomes, in line with J. Heckman et al. (2010). The two noncognitive traits we examined and found to be of great significance were extraversion (looking at the student relationship with the teacher through the frequency of student-teacher dialogue) and conscientiousness (by looking at the time the student spent studying). Consistent with the results concerning adolescents' non-cognitive skills found by Jackson (2012) and Tough (2013), our study also identified a significant impact on the non-cognitive skills of grade 8 students, i.e. those in their last year of junior secondary school. This suggests that lesson study could help achieve higher student motivation through improved extraversion and conscientiousness; in turn, this could well lead to greater academic achievement in upper secondary school when longer time horizons are considered than in our study.

Teacher development
Tables 4-6 present the results for teacher development through lesson study. Table 4 describes the results of the teacher's understanding of what the student knows in the subject, before and after lesson study. There is evidence that teachers' understanding of student knowledge in their lessons increased considerably, a statistically significant result in Math, English, Biology, Chemistry and History. Tables 5 and 6 present the results concerning teacher engagement with students inside and outside the classroom, indicators of interactive teaching. The teacher's engagement skills during lessons (Table 5) improved considerably in most subjects-except Literature and Physics. The results concerning the teacher's engagement skills outside the lesson (Table 6) are almost the same as those during the lesson, except that, interestingly, the result for Literature is now statistically significant.
We also found that lesson study had a significant effect on teacher performance: better understanding what their students know, together with more proactive engagement both inside and outside the classroom. These findings are consistent with previous research (Alamri, 2020;Dudley et al., 2019;Lewis & Perry, 2017), and the findings reinforce what is known about the effect of lesson study on teacher development. We do not have enough data to understand why the results are different for Literature and Physics but can speculate that possibly the teachers of these subjects were less motivated about lesson study than were teachers of other subjects. Table 7 shows that Vietnamese parents put a great effort into their children's education.

Parental engagement
As a result of lesson study, parents increased the attention they paid to check their children's homework and examination results, and also spoke more frequently with their children's teachers. All these parental involvement findings are statistically significant. While straightforward, this is another important finding of our study, as no previous studies have looked at the impact of lesson study on parental engagement.

Conclusions
This study has drawn on survey data about lesson study in a rural part of the Thanh Oai district of Vietnam to investigate student non-cognitive skills development through lesson study along with student cognitive skills development and teacher development. Specifically, this study has addressed student non-cognitive skills development in terms of student's extraversion and conscientiousness traits (two of the Big 5 traits), student cognitive skills with exam results, changes in teacher development, and changes in parental engagement.
Overall our results demonstrate a strong effect of lesson study in improving three important aspects of lower secondary school education: 1) student non-cognitive skills development, 2) teacher development, and 3) parental engagement. We did not, however, find an effect on students' academic achievement as had several previous researchers investigated (Arani et al., 2010;Cerbin & Kopp, 2006;Perry & Lewis, 2009;Saito & Atencio, 2013). Additionally, Arani et al. (2010) found that lesson study is more consequential for students at the primary education  level. Nonetheless, our study found important new results: that lesson study could improve students' non-cognitive skills at the lower secondary education level as well as increase parental engagement, aspects not previously studied. This provides a good starting point for further research on the impact of lesson study on student non-cognitive skills, especially at the lower secondary education level. Non-cognitive skills have been shown by Kautz, Heckman, et al. (2014) to be very important to improve both academic achievement and life outcomes. Improving non-cognitive skills through lesson study activity at the lower secondary level may well have implications, therefore, for academic outcomes at the upper secondary and higher education levels as well as for life outcomes including behavioral and labor market outcomes, as mentioned by J. J. Heckman et al. (2006).
However, future research should consider more carefully the causal effects of lesson study on students' skills development. A limitation of our study, for example, is that our small data sample does not permit us to analyze these causal effects. Nor do we look at all five of the widely accepted Big 5 non-cognitive traits-future research could usefully add Openness to Experience, Agreeableness and Neuroticism/Emotional Stability to our studied traits of Conscientiousness and Extraversion. A further limitation is the very short period of only two months between the before and after measurements of skills. Finally, it is only a study of one school in one district and needs to be supplemented with analyses of more schools in more districts, including schools whose students were not performing so well in advance of the introduction of lesson study. To the best of our knowledge, no analysis has been made in Vietnam of the costs of introducing lesson study or of the best ways to do it. Such research would also be very valuable.
Without such further analyses, it is difficult to draw broad policy implications for Vietnam. Our results suggest, however, that lesson study can improve non-cognitive skills at the upper secondary level. More work is needed into whether or not it can improve cognitive skills, a finding of some other studies but not of ours.

Biology
I have a good relationship with my Chemistry teacher. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher understands what I know. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher questions and speaks to me frequently in the classroom.
□Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher questions and speaks to me frequently outside the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree Chemistry I have a good relationship with my Chemistry teacher. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher understands what I know. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher questions and speaks to me frequently in the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Chemistry teacher questions and speaks to me frequently outside the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree

Physics
I have a good relationship with my Physics teacher. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Physics teacher understands what I know. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Physics teacher questions and speaks to me frequently in the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My Physics teacher questions and speaks to me frequently outside the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree History I have a good relationship with my History teacher. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My History teacher understands what I know. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My History teacher questions and speaks to me frequently in the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree My History teacher questions and speaks to me frequently outside the classroom. □Strongly agree □Agree □Neither disagree nor agree □Disagree □Strongly disagree 4. Please check the box to indicate how many hours you study at home in each subject every day.