The aim of this study is first to investigate what kind of class profiles can be identified in Finnish schools in terms of student background and then examine how students’ mathematical reasoning develops in different types of classes from grade 4 to grade 6. In Finland, differences in student performance are found between classes rather than between schools. Students are not randomly assigned to classes, and for example, students special educational needs or their previous academic performance can affect the placement decisions (Paufler & Amrein-Beardsley, 2013). When student allocation is not random, it can be expected that students’ performance develops differently depending on the class they are assigned to (Hienonen, 2020). Data for the present study will be drawn from a longitudinal study with a nationally representative sample. Data were collected in 2022–2024, following the same students from grade 4 to grade 6 (2000 students from 110 classes and 75 schools). The research questions are: 1. What kind of class-level profiles can be identified based on different student background factors? 2. How does students’ mathematical reasoning develop in classes with different profiles? For the research questions 1 multilevel latent class analysis will be used to estimate different subgroups. For the research question 2, multilevel latent growth curve modelling will be utilized to investigate the developmental trajectories of mathematical reasoning in classes with different profiles. All analyses will be conducted in MPlus. Student’s background variables are mainly derived from student information forms completed by teachers and from the student questionnaire. Information on students’ class placement is derived from principals.  Student performance is measured with adaptive mathematical reasoning task. For the student-level and class-level profiles, also cognitive tasks in inductive reasoning, verbal reasoning and problem solving will be used.

Hienonen, N. (2020). Does a class placement matter? Students with special educational needs in regular or special classes. University of Helsinki. http://urn.fi/URN:ISBN:978-951-51-6392-9 Paufler, N. A., & Amrein-Beardsley, A. (2013). The random assignment of students into elementary classrooms: Implications for value-added analyses and interpretations. American Educational Research Journal, 51, 328–362. doi.org/10.3102/ 0002831213508299.