Most RCT studies stop at the post-test stage, without follow-up observations. Stephens and colleagues conducted a study to examine if an early algebra intervention influenced later learning. Participants were 1,455 students from 46 elementary schools. Seven hundred and sixteen students were from 23 treatment schools that used an early algebra intervention for 18 one-hour lessons per year from third through fifth grade during regular math class. The rest were from 23 control schools. All the students moved to a new middle school in grade 6.

Students completed an 11-item written assessment before and after the intervention.

• Overall, the treatment group (M = 47.51% correct, SD = 21.54%) did better than the control group (M = 37.93% correct, SD = 19.74%) in the initial year of the intervention.
• However, the gap between the two groups narrowed from Grade 5 to Grade 6. Control students experienced an overall increase in performance from Grade 5 (M = 33.38%, SD = 19.43%) to Grade 6 (M = 37.93%, SD= 19.74%), and treatment students experienced an overall decrease in performance from Grade 5 (M = 53.40%, SD = 24.17%) to Grade 6 (M = 47.51%, SD = 21.54%).
• Results also showed that the control students improved in algebraic ideas and thinking practices, like deeper understanding about equivalence. But they still lagged the treatment group, who continued to present good results.

This study provides evidence that it is useful to give students an early algebra intervention, which could be to their advantage when they enter middle school.

Source: Stephens, A., Stroud, R., Strachota, S., Stylianou, D., Blanton, M., Knuth, E., & Gardiner, A. (2021). What early algebra knowledge persists 1 year after an elementary grades intervention? Journal for Research in Mathematics Education, 52(3), 332–348. https://doi.org/10.5951/jresematheduc-2020-0304