A research project was conducted to study the effects of an 8-week prekindergarten enrichment program and of two 15-month preschool enrichment programs. Pretest and posttest scores of experimental and control kindergarten children (a sample of 100 out of 1,000 subjects) showed that both groups made significant gains in all ability categories o f…

A study was conducted to determine if the observed changes in Head Start children were related to the practice effects inherent in a test-retest situation. The "control" group consisted of 64 children who had been eligible for a Head Start program. They roughly matched a group of Head Start (HS) children in IQ scores, age, and…