Families were randomly assigned to one of two groups: the intervention, and a control group. For 2 years during the regular school year (39 weeks a year), 3-4 year old children would come to a classroom for 2 and a half hours a day. Students worked on projects where "they planned tasks, they executed tasks, and then they reviewed the tasks collectively."[1] The intervention also included weekly visits by the teachers to the homes of the children for about 1.5 hours per visit to improve parent-child interactions at home.[8]