Abstract
This article reports on the effectiveness of an intervention using conceptual change approaches within challenging tasks, on the mathematics gains for low-performing year 3-6 students in in six primary schools. Quantitative data from PAT-Maths testing for each year showed a consistently large effect size of 0.7 compared to expected gain data from DECD. All six experimental groups caught up with DECD expectations within one year. Over the two years, students from years 3-5 gained an additional 27 months of mathematics learning over the expectations and students from years 4-6 gained 29 months, indicating the potential of the approach for closing educational gaps for low-performing students.