Effectiveness of Layered Curriculum: A Mixed-Meta Research Synthesis
Abstract
The mixed-meta analysis study aims to examine the effects of the layered curriculum on students based on the studies conducted between 2006 and 2021. The statistical data gathered from a total of five studies is indexed in national databases investigating the effect of layered curriculum on achievement and attitudes, and the overall effect of the layered curriculum on achievement is found to be moderate, while its effect on attitudes is found to be very large. In the qualitative part of this mixed-meta analysis, the meta-thematic analysis method is conducted through document review and content analysis of a total of nine studies, and codes are classified under the themes of cognitive domain, attitudinal dimension, and limitations. These themes are visualized in the Maxqda program and presented in the findings section in two models. Some of the codes in the cognitive domain are increased academic achievement, permanence, repetition, peer assessment, self-evaluation, creativity, and imagination. In the dimension of attitude, codes are collaborative learning, aroused excitement, desire, and curiosity towards the lesson, increased interest, increased in class solidarity, and student motivation towards the lesson. Limitations such as the lack of focus in the classroom because of noise, the difficulty of students with no manual dexterity, the need for detailed planning, the difficulty of creating an original product, and the lack of time are turned into a second model on their own as a theme. Suggestions regarding time management, comprehension of schedules and tasks, class size, and planning are presented to address the difficulties encountered in the studies. The current study provides insights into the effects of a layered curriculum on achievement and learning attitudes.
Keywords:
- Layered Curriculum
- Mixed-Meta Method
- Meta-Analysis
- Meta-Thematic Analysis
- Achievement
- Attitudes
Introduction
With the development of technology, today's world is changing rapidly, which also profoundly affects society, industry, housing, transportation, and education. The expectations of society from its individuals are constantly changing in line with the evolving needs. While individuals are expected to hunt in agricultural societies, they are expected to use machines effectively in industrial st societies. In the 21 century, the social, economic, and political developments brought about by advancements in technology have made it necessary for people to acquire different skill sets. These skills, generally referred to st as 21 century skills, have been defined in more than one framework (Cansoy, 2018). Although definitions are placed in different frameworks, education is always tasked with providing these qualifications.
In order to acquire the determined qualifications, it is necessary to move away from the traditional education model where the teacher is at the center and imparts information to the student in a one-way manner. It is essential to transform instruction into a model that centers on the actively participating and experiencing learner throughout the education process. In the 2023 education vision document published by the Ministry of National Education of Turkey, the aim is to raise individuals who internalize learning and focusing on individual differences. One of the differences between the new approach and traditional education is that it emphasizes the autonomy of the student in the learning process, and another is that individual differences are not ignored.
The readiness of each individual in a learning environment is not the same. Learning styles also differ from person to person, as the dominant intelligence dimensions, thinking systems, and problem-solving skills also vary. Along with multiple intelligence theory and constructivism, which emerged from the fact that each person learns differently, the layered curriculum is one of the approaches based on individual differences (Demirel et al., 2006; Gün & Şahin, 2014).
1. Layered Curriculum
Traditional education, where all students learn the same way, is now outdated. The biggest difference with new teaching techniques is that students learn in different ways. While some learn orally by reading, others cannot learn effectively by reading and instead learn more effectively with audio-visual materials (Güven, 2004). Some students learn effectively in groups, while others learn effectively by doing individual work. Some learn by breaking information into pieces and reaching the whole, while others organize information as a whole more easily. According to Oluk et al. (2007), the first studies that suggested individuals have different learning styles were the studies of Rita Dunn on learning styles in the 1960s. According to Dunn, learning styles refer to students' use of their own unique ways to learn or remember new information (Koç, 2013).
Based on these studies, educational psychologist Katie F. Nunley introduced the layered curriculum, which is based on the idea that each student's learning style is different. Nunley believed that tailoring education to these differences would lead to more lasting learning experiences. Drawing on the work of Rita Dunn and influenced by Gardner's theory of multiple intelligences, Nunley developed the layered teaching model, which is based on the principles of learning from simple to complex, from concrete to abstract, from known to unknown, and from easy to difficult. As the name suggests, information is presented in a step-by-step manner(Aydoğuş, 2009; Koç, 2013).
The teaching process should be structured into levels with different depths. There are different types of information in each of the levels called A, B, and C, and the type of information and responsibility that should be given at each step is different from each other. The levels have different depths and complex structures. Level A contains more complex information and a higher level of thought than level C and level B. Each level has tasks with different complex structures. These tasks require skills that the student can choose on their own, take the individual to higher thinking skills, and give the student responsibility for learning.
The C level is the lowest level and explains the basic concepts and main frame of the subject. Remembering and understanding are fundamental concepts at this level. The tasks at this level are those that teach and remind the student of the basic concepts and key information. Individuals gain basic knowledge and skills at this level.
In level B, there are tasks for using and processing the information learned in level C. New knowledge should be compared with existing or different knowledge, and at the same time, the aspects to be used should be supported. In the tasks defined for level B, the student should be able to solve the defined problem, compare the information they will use while solving the problem, and explain the subject in different ways. The tasks in this level should be more difficult than the tasks in level C but easier than the tasks in level A. It should prevent the student from staying on the C level and allow them to move on to the A level. Going beyond acting on available information, in level A, it is expected that new ideas and products about the target concept and information will be revealed.
At this level, which requires the use of higher-order thinking skills, the individual should be able to analyze and evaluate the information or product. The tasks in level A should make students critically approach the original product or original thought, use high-level thinking skills, and gain cognitive awareness (Nunley & Gencel, 2019).
The layered curriculum and Bloom's taxonomy share some similarities in cognitive processes and knowledge dimensions. The characteristics of factual knowledge in the knowledge dimension of the revised taxonomy can be associated with tasks at level C, the features of procedural knowledge with tasks at level B, and the features of metacognitive knowledge with tasks at level A. However, the features of conceptual knowledge can exist at both the C and B levels. The layered curriculum has a structure that is very similar to the cognitive process dimension of the revised Bloom's taxonomy in terms of its gradual progression principle. Remembering, understanding, applying, analyzing, evaluating, and creating can be aligned with relevant levels in the layered curriculum.
Since the definition in the remembering phase of the taxonomy says that translating, sampling, classifying, deducing, and explaining in the understanding phase are among the features of level C tasks, they can be placed in the remembering and understanding phases of level C. In the tasks of level B, the problem-solving content and the application phase are directly matched. Identifying the differences, organizing the subject, presenting evidence, critical thinking, planning, and developing new and original products are also the contents of the analysis, evaluation, and creation steps in Bloom's taxonomy (Krathwohl, 2002). It is expected that after learning the content in level C, the individual will put it into practice in level B and be able to synthesize a new product or evaluate a product by analyzing the information in level A.
The quality of the curriculum is not only determined by the quality of the objectives, content, and learning-teaching situations but also by the functioning of the measurement and evaluation elements. Individual differences should be taken into account not only in the learning and teaching process but also in the evaluation process. Evaluating students' learning at their own pace is the basis of the layered curriculum that prioritizes individual differences. Evaluating each student at their own pace also has a positive impact on their motivation (Başbay, 2005). The more active use of process evaluation instead of product evaluation in a course organized according to the layered curriculum increases the benefit of the curriculum. It is also important to have questions at different levels and to determine the appropriate criteria for each level in the layered curriculum.
The most effective method that can be used to take individual differences into consideration is oral assessment. In this type of assessment, the assessment should be conducted in a conversational atmosphere so that the student does not feel as if they are being questioned in the classroom (Yıldız, 2018). Talking about the original answers and obtaining additional information from the student with alternative questions when appropriate, leads to a more detailed and objective result in the evaluation of the individual (Biçer, 2011). In fact, the important thing is not to complete the tasks, but to measure how much of the targeted learning has taken place. The layered curriculum also allows for self -assessment and peer assessment (Özdemir, 2019). The program is prepared in advance by the teacher, and the tasks at each step are determined in accordance with the steps. It is clear from the beginning what is expected of the student with the determined tasks. The person is also aware of the criteria. Since the student determines the task in advance, it is also a supportive application for classroom management, because everything that can be objected to has already been addressed. Each individual in the learning process has chosen and accepted their own task (Gün, 2012).
2. Purpose and Significance of the Research
The study aims to identify whether students' achievement and attitudes towards the course changed after applying the layered curriculum in different course areas. The studies using the layered curriculum during the teaching of a subject or unit are examined and analyzed interpretively and in detail. This study seeks to create a scientific basis for teachers and educators who wants to use the layered curriculum in their lessons, determining whether or not the program works effectively. Teachers and educators can consider the precautions to be taken before putting the application into practice by referring directly to the students' opinions in the reference studies of the codes extracted under the theme of limitations.
The layered curriculum, which is based on individual differences, proposes that each student has different learning styles throughout the educational process. The curriculum can be used at every step of the education process and allows individuals to evaluate themselves and their peers and choose their own learning tasks. The program, which can be adapted to many course areas, is also suitable for Bloom's taxonomy. It is very important that individual learning styles can emerge in many different ways in a classroom. The layered curriculum can be applied to see the learning styles of the students in the classroom and measure their level of success based on how well they perform tasks at different levels. The interest, enthusiasm, and curiosity of the students taught with the layered curriculum increase, resulting in a positive change in their attitude towards the course and academic success, leading to increased self-confidence (Öner, 2012).
The program has a positive effect on the students not only in the cognitive domain but also in the affective domain (Kahraman & Gündoğdu, 2021). The positive and negative findings related to the program's implementation can be obtained by reviewing the studies in the literature. This study employs a mixed method approach that combines meta-analysis, which involves the analysis of quantitative studies, and metathematic analysis, which involves examining qualitative studies from an interpretative perspective (Ozdemir, 2019). The study aims to contribute to the literature both quantitatively and qualitatively by investigating the overall effect of the layered curriculum on achievement and attitude.
- What is the overall effect of the layered curriculum on students' achievement and attitudes?
- What are the cognitive effects, attitudinal effects and limitations of the layered curriculum?
3. Method
The mixed method, which allows researchers to seek answers to research problems by blending quantitative and qualitative methodologies, methods and paradigms, has gained importance recently. Although many definitions have been made for the mixed method, from a methodological point of view, the mixed method is the collection and analysis of data by blending qualitative and quantitative methods in a study (Toraman, 2021). The mixed method used in different disciplines has a basic principle of combining the strengths of the hypotheses put forward by researchers and not multiplying their weaknesses. In this type of research, qualitative and quantitative methods can be blended, or the researcher may work with partly quantitative and partly qualitative methods. It provides an opportunity to look at the same research problem from different angles (Balcı, 2021).
The mixed-meta method, on the other hand, is a method that combines the meta-analysis process in a quantitative sense and the meta-thematic analysis process in a qualitative sense. In this analysis, scientifically accepted or published studies are reinterpreted by the researcher in a quantitative and qualitative paradigm. In the meta-analysis part, the effect size value, which is a statistical data obtained from applications such as CMA or MetaWin, constitutes the finding of the meta-analysis study. The findings of the meta-thematic analysis, on the other hand, consist of codes that the researcher extracted from the participant's views and thematized under common headings (Batdi, 2019). In this study, the effect of the layered curriculum on achievement and attitudes was measured with the use of the mixed-meta analysis method, which consists of a meta-analysis for the quantitative part and a meta-thematic analysis for the qualitative part.
3.1 Meta-Analysis
In quantitative studies where a phenomenon is being tested, meta-analysis is the process of analyzing whether the phenomenon works and, if it does, how effective it is. The aim is to examine the effect of each of the quantitative studies and reach a general conclusion about the research problem. The concept of "effect size" emerges by using the standard deviation, arithmetic mean, and sample size in the studies included in the analysis. The direction and magnitude of the effect in the studies can be understood by calculating the effect size value. The effect size value shows the numerical comparison of the relationship between the two variables (Borenstein, 2009). During the meta-analysis process, the answers to be reached include whether the studies on the same subject make sense together, how much they confirm each other, and how effective the studies are at generalizing the results. Integration and generalization of studies in the literature are advancing with meta-analysis studies (Büyüköztürk et al., 2016).
It is very difficult to generalize quantitative studies in the social sciences. However, meta-analysis studies provide convenience to researchers in making this generalization, albeit partially. As the effect level is determined separately for each study, there is also an average effect value for all studies included in the analysis (Dincer, 2021). The meta-analysis process is important because this mean value allows for generalizations about the level and extent of the effect of the concept that is the subject of the research. It is quite appropriate to define the analysis of meta-analysis as the result of reanalyzing the studies that have been analyzed before (Glass, 1976).
3.2 Meta-Thematic Analysis
Meta-thematic analysis aims to combine the qualitative findings of studies on a particular subject in the relevant literature into codes and themes. One of the criteria for including a study in the analysis is the first-hand presentation of the participants' opinions. Obtaining participant opinions directly from the studies means that the researcher has access to raw data. Raw data refers to data collected for research that has not passed through any filters. While the opinions of the participants are the data for the meta-thematic analysis, the codes extracted without deviating from the essence of the opinions constitute the findings of the analysis. The extracted codes are thematized under headings. The purpose of meta-thematic analysis is to combine the findings of qualitative studies in the context of a topic. The themes and codes created based on the findings reflect the researcher's perspective. In this process, the researcher reinterprets the views without breaking the originality of the participants' opinions. The search for a reinterpretation of views prevails (Batdi, 2019). Meta-thematic analysis is the process of extracting themes and codes through the content analysis of documents.
In document review, the researcher has the opportunity to access the data required for the research without making observations or conducting interviews. Document review is a very practical method for researchers, and it also increases the validity and reliability of the study by diversifying the data in qualitative studies (Yildirim, 2016; Yıldırım & Şimşek, 2021). The inductive framework is used to reach general themes from each of the studies included in the analysis. One of the underlying philosophies of meta-thematic analysis is embedded theory. According to this theory, the researcher should reach the underlying information in the relevant literature by conducting a literature review. This information includes the codes extracted by meta-thematic analysis. Meta-thematic analysis involves a more complex structure than merely taking opinions directly from studies and combining them. What is important is being able to interpret, relate to, and make sense of this unification path. Meta-thematic analysis is the thematization of themes (Batdi, 2019).
4. Collection and Analysis of Data
National databases are scanned to find the studies that will be examined through meta-analysis based on the document review. When scanning the databases, the concept of a "layered curriculum" is used. As a result of the scans, the standard deviation, sample size, and arithmetic mean values of the post-test achievement and attitude scores of both the experimental and control groups from the quantitative studies conducted during the period 2006–2021 are included in the analysis. Statistical values from quantitative studies give the effect value that constitutes the finding of the meta-analysis. Of the five studies included in the meta-analysis, four are taken from Yöktez, the Turkish National Theses Database, and one from Google Scholar. Thirteen data are obtained from four studies on achievement, and three data are taken from three studies for the attitudes part. Statistical analysis software such as MetaWin or CMA is used for meta-analysis. In this study, a program called Comprehensive Meta-Analysis, abbreviated as CMA, is used to find the effect size value.
By entering the necessary statistical data, the effect value of each study and the average effect value of the five studies included in the analysis are calculated. If the effect value is positive, it means that the intervention made on the experimental group gives a result against the control group, while a negative result produces a result in favor of the control group. In general, although the greater the effect value is under the absolute threshold, the wider or higher the effect, the more widely or highly effective it is, but different researchers have evaluated the effect value at different intervals. The effect level value of the meta-analysis finding of this study, in which the achievement and attitude effect of the layered curriculum is measured, and is evaluated according to Thalheimer and Cook's effect-size classification. Thalheimer and Cook divided the magnitude of the effect size into six ranges. If the effect value is greater than 1.45, it means a huge effect, if it is between 1.45 and 1.10, it means a very large effect, if it is between 1.10 and 0.75, it means a large effect, if it is less than 0.75 but greater than 0.40, it means a medium effect, if it is in the range of 0.40 and 0.15, it means a small effect, and if it is less than 0.15, it means a negligible effect (Thalheimer & Cook, 2002).
In Google Scholar and Yöktez, the National Theses Databases, "layered curriculum" is searched, and studies and applications related to it are included. Studies conducted between 2006 and 2021 are selected, in which the opinions of participants such as students, teachers, and observers are expressed first hand. Nine studies with raw data are included in the analysis made between the specified years, one of which is an article and eight of which are thesis files. The article is obtained from Google Scholar, and the thesis files are obtained from Yöktez. In the data analysis part, the opinions of the participants are examined using the content analysis method. Content analysis enables an in-depth examination of the available data to reveal common information embedded in the studies. An inductive approach is effective in the content analysis process as it allows a detailed framework to be reached (Yıldırım & Şimşek, 2021). As a result of these examinations, the codes extracted by the open coding method are classified under three themes.
Attention is paid to internal consistency between the codes categorized under themes. It has also been taken into account that a code must be externally consistent so that it does not belong to different themes. While the expression M1 in the section where the meta-thematic analysis is included under the title of findings is the code of the article included in the analysis, six-digit numbers, such as 174191, indicate the thesis numbers of the theses in the Yöktez database. For example, a statement such as "s. 45" next to the thesis numbers means that the code is omitted from the views on page 45 of thesis 174191.
5. Results
The meta-analysis process of the current study consists of two parts, analyses are conducted on the effect of layered curriculum-based practices on learners' achievement and attitude scores (Basbay, 2006). When examined in the context of the mixed-meta analysis method, the findings are analyzed in two stages, quantitative meta-analysis data for the studies reached in the first stage and meta-thematic analysis data with qualitative content in the second stage are presented by modeling them. Table 1 shows the homogeneous distribution value, average effect size, and confidence intervals according to the effect models of the studies included in the meta-analysis findings
Table 1. Homogeneous Distribution Value, Average Effect Size and Confidence Intervals According to the Effect Models of the Studies Included in the Meta-Analysis
Table 1 shows the Random Effects Model (REM) analysis showed a standard error of 0.113, an upper limit of the 95% confidence interval of 0.961, a lower limit of 0.517, and a mean effect size of 0.739 in the context of achievement scores. This finding suggests that learning achievement is better with layered curriculum-based practices compared to traditional teaching methods Based on Thalheimer and Cook's (2002) classification, the effect size value is considered to be at the medium level, i.e., 0.40 ≤ effect size value < 0.75. Thus, the analysis is statistically significant, with a result of p = 0.000. The homogeneity test has yielded a statistical value of Q as 29.317.
As a result of the analysis, it is concluded that if 337 and 56 more studies on the effect of the layered curriculum on achievement and attitude scores are included in the analysis, the significant effect would decrease to zero. When the number of studies reached is examined, it can be said that it may be difficult to reach so many studies. This can be interpreted as the absence of publication bias. However, when the Egger test result is examined, there is no significant difference as a result of the analysis of the achievement scores (p > .05), while the Egger test result for attitude scores is found to be significant (p < .05). The fact that this value is insignificant can be considered as non-publication bias. Figure 1 shows the visualizations of funnel charts of attitude and achievement scores from the meta-analysis dataset.
Figure 1. Funnel Charts for Achievement and Attitude Scores
In this study examining the achievement and attitude effects of the layered curriculum, codes extracted from raw data in the analyzed studies are classified into three main themes, limitations, cognitive, and attitude. The Maxqda program presents the first model of the study, which includes the cognitive and attitude themes, and the second model, which focuses on the limitations theme.
In the cognitive theme part of the effect of the layered curriculum on cognitive and attitude dimensions, some of the codes are, inter-relationship grounding, suitability for students with different learning styles, peer evaluation, development of self-control and self-evaluation skills, and active participation in the course, subject repetition, and increased permanence. The sentences used as a reference to the code "of making grounding between relationships" are,
"The climate in our country is not very diverse because Atiro is a small island. There are not many changes in landforms. Our country is far north and vulnerable to cold winds and storms from the north. Therefore, the people of Atiro had to take great precautions against storms and developed their thermal insulation systems. Our island is located in the north of the Atlantic Ocean. There are deep bays called fjords around the island. The coastal areas are low plains, and the interior is high plateau-shaped. Some of the mountains that rise in these highlands are volcanoes that are still active and erupt lava from time to time. I have already covered this in environmental issues" (174919, p.95).
The sentences used as a reference to the code "using problem-solving steps" are,
"I had a hard time writing poetry on step B. I asked my teacher because I didn't know how to write poetry. My teacher gave me some advice, and I immediately scanned the sources. I also asked my Turkish teacher and put my knowledge together. Finally, I wrote the poem and presented it in class. My friends and teacher asked me questions. When I was writing a story on step A, I followed the same path, and it was easy for me... " (174919, p.93).
The fact that the student determines the problem, conducts research on how to solve it, examines source materials, and reaches a solution indicates that the student is using problem-solving stages.
"... then we tried to complete the assignment on time..." and "He showed me that I needed to be more effective in my research and to hurry up. We have to complete it three times a week, or we won't get a certificate of achievement from C..." (174919, p.93).
The code to increase time management skills is extracted from the student's opinion. The sentences used as a reference to the code "increasing academic success" are,
"It helped me get better scores than the written ones" and "It allowed me to perform better in the course and achieve higher scores on exams" (289694, p.85).
Furthermore, "I have definitely observed a change in the students' academic achievements, especially in the fifth grade I entered two years ago where academic achievements have increased..." (174919, p.131).
The statement that supports the extracted code is,
"It helped me learn the subjects. In the first test we did, we made many mistakes, but in the last test, I made fewer mistakes. It increased my success" (319657, p.104).
Regarding the concept of individual differences underlying the layered curriculum, the statement "students chose activities according to their own comprehension and learning abilities" is taken as a source for the code.
"Being suitable for students with different learning styles" (M1, p.82).
The code "embodying the relationship of subjects to daily and current life" is based on the statements,
"My teacher is the same in cartoons. The world gets so filthy, and they go to another world" (263140, p.102). "Today, he uses it in social studies, and tomorrow when he moves to university, he can transfer it to other areas. Or the fact that he's using a topic that he sees in social studies here, yes, I can use this information, it helps me to create this idea" (174919, p.112).
Some of the codes drawn from the effect of the layered curriculum on the attitude dimension include "putting out products gives pleasure to the student," "offering the opportunity to learn by having fun," and "allowing pleasure and originality in the course." For the code "of arousing excitement and curiosity towards the lesson, increasing interest," the following statements are relevant,
"The application of this method aroused positive emotions towards science and technology lessons. I wanted this lesson to come every week," "I became more interested in science and technology," and "But with these activities, I started to focus on science and technology. I've been eagerly awaiting the lesson" (289694, p.91).
At the same time, Hilal, a student mentioned on page 104 of study number 263140, said,
"I never looked at the science and technology book. When these events happened, I started looking, I was curious" (263140).
The code "giving the person the ability to be responsible" is based on the statements,
"I learned to take responsibility in individual work..." (174919, p.100)
"It gave me responsibility." "I think I'm taking responsibility because I'm doing it one day" (617499, p.123).
The code "increasing communication and solidarity within the classroom" is formed based on the statements,
“... It has had positive effects because in the classroom environment, everyone gets help from each other. They do it together, and they help each other..." "... Actually, it didn't contribute to my class average because we haven't graded it yet, but it contributed to our friendship because we did some of it with my friends..." "... I helped my friends on some steps. This influenced our teamwork..." and "... When I was doing activities with my friends, a strong bond was formed, and it allowed us to be better friends..." (617499, p.131).
Büşra said,
"It was very nice to choose the activity we wanted. We can do what we want according to ourselves” (315041, p.71).
The code “feeling comfortable with knowing how to handle the process” is based on the statements,
"It is a very nice thing to do things that we have chosen," "... Fatih teacher gave us photocopies of what we were going to do. We can go to science class now knowing what to do" (263140, p.87).
"... and it was fun. So we were repeating topics in a fun way." "To me, everybody's been fun, so everybody seems to be having fun because it's really fun work" (174919, p. 114).
The statements,
"... it was very nice, I had a lot of fun. Our lesson was a lot of fun..." and "Dear Diary, We have presented our activities on this day. It was very, very fun. Some sang, some played games with the TV..." led to the emergence of the code of “offering the opportunity to learn by having fun”. The statement on the page, "... Although it was a bit challenging, it was fun and instructive..." and "Because I have a lot of fun doing it and I understand English better, and that's why English has started to feel a lot more fun to me"
Also contributed to the formation of this code. Figure 2 metashows the cognitive and attitude themes model.
Figure 2. Cognitive and Attitude Themes Model
In this study, which investigates the effect of the layered curriculum on achievement and attitudes towards classes, the meta-thematic analysis findings establish the theme of limitations of the layered curriculum. Regarding the codes formed within these limitations, some examples include lack of information about how to do tasks, classroom noise leading to a lack of focus, insufficient time, requiring detailed planning, and a problem of in-group harmony. The source of the code "noise in the classroom leads to lack of focus" is the statements,
"There was a bit of noise in the crowded classrooms," "From time to time, I was disturbed by the noise of my friends" (M1, p.84).
"There is noise in the English lesson, and they disrupt the lesson a lot. That's why it's sometimes very difficult to focus on the lesson..." (617499, p.123).
Excessive criticism negatively affects the students. A student states,
"I had a slideshow today. I showed them. The comments made by the class broke me a lot." "I was going to be the first to present my event. And they were very critical of my title. Oh... They were jealous of me because... Huh... It was Güler's turn. He criticized me and said: "Mine is more beautiful than Hilal." Of course, it made me angry" (263140, p.92).
"So there's already a problem with one going from A and one from Z. So what's the biggest problem is, you find their partnership, and that partnership lasts a month or two. It doesn't take a whole year. That's how you try to make a project. After one is finished, the other joins. So it can't be processed at the same time" (174919, p.118).
The fact that the subjects are covered in different courses at different time periods has affected the integrity of the teaching process. This has led to problems with the functioning of the tasks on the steps. The code "that the time is not enough" is based on the statements,
"Sometimes I could not keep up with the study, and I had difficulty at that time. In some courses, we do not
have enough time for our research. Or let's say the time is enough, we move on to class, we can't offer it", and "it is necessary to put them in a certain file..." (263140, p.153; 174919, p.115).
The code "requiring detailed planning" is based on the statement,
"So, for example, in the summer period, in the summer seminars, in August, June, we are supposed to sit down and discuss with the teachers of that lesson for a long time and plan everything beforehand" (174919, p.128).
The code "lack of knowledge about how to do the tasks" describes that students have difficulty producing original products,
“He said, 'I had a hard time writing poetry on Step B. I asked my teacher. I didn't know how to write poetry. My teacher told me a little bit. "I had trouble with Step B because I didn't know the slide." "I didn't have as much trouble in C, but in B, when I was writing poetry, I tried to write different things. It was hard to make them," and "I had a little bit of a hard time finding the rhythms when I was writing lyrics on Step B" (370138, p.198; 370138, p.199; 370138, p.176).
For the code "forcing students without skills," the statements taken as references are,
"What I had difficulty with on Step A was drawing. My picture isn't very beautiful, so I drew over it. I drew it with covers or something." "There were so many problems in our group because there were always some people working and others were sitting. I struggled to keep up with their missions" and "Because, like I said, some of them weren't doing their job at all, they were causing us to have more shortcomings in our group" (174919, p.118-119).
Figure 3 shows the limitations theme model.
Figure 3. Limitations Theme Model
The first research problem is answered in the meta analysis findings. At the end of the research process, the effect of the layered curriculum on achievement is moderate, and the effect on attitudes is very large. The three main themes that emerged in the context of metashows thematic analysis are visualized in two models using the Maxqda program. These themes provide answers to the second research problem. In the limitations theme, negative comments that arise during the program's implementation are taken as references, while the cognitive and attitude theme is created through the positive comments in the literature. Possible problems are likely to occur during the implementation of the layered curriculum. However, despite the negative aspects, the implementation of the layered curriculum makes positive contributions to the students in many ways, both quantitatively and qualitatively.
Conclusion
In the 1980s for differentiating instruction based on learner differences. Since then, this approach has been espoused by teachers around the world and has been researched for its effectiveness in various school subjects and at different school grades. The present study is designed to reveal the overall effect of the layered curriculum approach on learning achievement and attitudes by using a mixed-meta method. The national research literature on the layered curriculum is reviewed and re-evaluated, and the studies containing the necessary data from the experimental and control groups from scientifically published quantitative studies are examined. Thus, the overall effect size value is calculated using the meta-analysis method. In the metathematic sense, the codes extracted from the participant opinions in qualitative studies are thematized and presented in the findings section. In the meta-analysis section, which is based on the re-analysis of the analyzed studies, the answer to the question of the level of effectiveness of the layered curriculum in terms of learning achievement and attitudes is sought. In the meta-thematic analysis section, the qualitative results of the layered curriculum on the participants are interpreted and presented in a meaningful way based on the information embedded in the studies in the literature.
Based on the findings of the meta-analysis, it is evident that the layered curriculum positively contributes to student achievement and learning attitudes. The effect of the approach on achievement is found to be 0.739, which represents a moderate level of effectiveness for the experimental group, according to Thalheimer and Cook's classification. The effect of the approach on attitudes is revealed as 1.251, indicating a very large level of effectiveness for the experimental group, according to Thalheimer and Cook's classification. It can be concluded that the layered curriculum, which has a positive impact on both achievement and attitudes, is more effective than traditional teaching methods. In Kahraman and Gündoğdu's (2021) study, it is shown that the layered curriculum has a positive effect in favor of the experimental group, based on the results of the Mann- Whitney U test of the final attitude scores. It is explained that the approach has a moderate effect in favor of the experimental group.
Yılmaz (2019) teaches geometric bodies to sixth-grade students according to the layered curriculum over a 4- week period in the mathematics class. It is concluded against the control group in the final attitude scores, and a statistically significant difference is observed. In Zeybek's (2016) doctoral thesis, it is found that there is no significant difference between the experimental and control groups in the results of the success obtained in a 12-week process. In the ANCOVA test, the results are analyzed again , and adjusted information, comprehension level, and total success scores are found to be highly significant in favor of the experimental group. However, there is no significant difference in application scores. In the study conducted by Yıldız (2018) to measure the effect of the layered curriculum supported by reflective learning on success and attitude, it is concluded that there is no significant difference between the success and attitude scores of the experimental and control groups. In the doctoral thesis, Yılmaz (2010) states that there is a difference between the experimental and control groups in terms of attitude scores, but this difference is not statistically significant.
The codes revealed by the meta-thematic analysis support the meta-analysis findings of the study. Although the codes fall under the theme of limitations, the positive results in the attitude and cognitive dimensions outweigh the negative aspects of the layered curriculum. Among the identified codes, the code of "feeling comfortable with knowing how to process the process" is supported by the code of "making myself feel comfortable" in the affective positive category of Kahraman and Gündoğdu's (2021) study, while the code of "making the lesson fun" is parallel to the code of "offering the opportunity to learn by having fun" in the attitude dimension of the study. The self-assessment code, which is included in the cognitive positive category, is also included in the "development of self-control and self regulation skills with self-evaluation" in the cognitive theme of the study. Canbulat et al. (2019) have identified similar codes such as active learning, having fun, exchanging information, and cooperation under the theme of benefits of the layered curriculum, based on the opinions gathered from the experimental group in their study.
Yılmaz (2010) concluded that, although a significant difference in attitude scores is not found quantitatively in the mixed-method study, the qualitative part of the study shows an increase in positive attitudes towards the course due to the increased interest and enthusiasm of the students. The students' reactions included starting to like the lessons. Yılmaz (2019) stated that the students who participated in the study always had positive comments about group work in their diaries, which contradicts the code of experiencing an intra-group adaptation problem under the limitation theme in this study. This finding is actually in line with the code of increasing communication and solidarity within the class, which is under the attitude dimension of this study.
Yılmaz stated that although there are problems with indiscipline, there are positive aspects of group work activities rather than negative results. The lack of material from the student is what makes evaluating the implementation of activities difficult. In the study conducted in the context of an English lesson, Üzüm (2017) extracted the code related to life, motivation, and fun under the title "student-centered" from the opinions of the participants. When asked which skills the layered curriculum contributes to developing in students, the study presented positive contributions to research and group work skills under the heading of basic skills by extracting themes from the students' answers. Although not evaluated within the scope of any theme in the study, codes such as getting more detailed answers to additional questions asked from the students, allowing the teacher to know the student in the selection of tasks, giving the ability to work individually, the layered curriculum being a method that supports the transferability of knowledge, allowing students to look at things from different angles, and allowing students to evaluate themselves at their own pace can also be inferred from the studies included in the analysis. Additionally, these codes are in line with the qualitative findings presented in the relevant literature.
It is found with the meta-analysis that the layered curriculum has a positive effect on attitude and achievement scores. The codes determined by the method of meta-thematic analysis are thematized as limitations, cognitive and attitudinal dimensions. The quantitative and qualitative findings of this mixed study support each other. The recommendations offered to educators who want to use the layered curriculum are,
- The courses, units and topics in which the study will be carried out should be planned in detail much in advance. As much as possible, the processing time of the subject in the curriculum covered in many field courses should be planned in a way that it shows parallelism.
- Students should be supported with materials
- In order to eliminate the problem of in-group harmony, groups of fewer people can be formed or the formation of groups can be left to the students.
- In order to avoid problems with the time, students may be warned to bring the necessary materials related to their duties, to collect useful information and to prepare before the lesson.
- Students should not be given tasks that require long processes in the tasks given, but tasks that they can accomplish in a shorter time.
- Students who do not have manual skills or who have little ability in this regard can be given tasks that are in their field of interest.
- In order to prevent the method from being perceived difficult, a positive atmosphere closer to the conversation can be created in the explanation of the program and visual or written examples can be made before it is presented.
- Because students don't know themselves well, students may be asked questions in advance to get to know them in order to prevent them from taking tasks that don't fit their interests or tasks on the wrong step.
- It can be applied in classrooms where the class size is less due to the noise in more crowded classrooms.
- It should be taken into account that students do not know how to perform the tasks and, if necessary, frames should be drawn as a guide to the tasks.