Mix, Kelly S.Smith, Linda B.Kindergartners were pre- and post-tested with a battery of place value concept tasks as well as mathematics outcomes after a 20-lesson intervention of place value instruction. Children were randomly assigned to either the instruction or active control group. If you would like a copy of the dataset(s), please send a written request to the study authors and data custodians, care of Dr. Kelly Mix (kmix@umd.edu).Dataset