Abstract:
Data collected from students involved in a project examining change in understanding of statistical variation in relation to the chance and data curriculum after instruction and after two years, are the basis for the analysis reported in this study. Comparisons are made, using partial credit Rasch analysis, between successive grades (3, 5, 7, and 9), within students after instruction, within students after two years, and between students in the four grades after two years depending on whether they were involved in the instructional intervention or not. Results show varying magnitudes of differences among grades, differing improvements after instruction, but little difference between Intervention and Non-Intervention groups after a two year period.