Achievement growth in children with learning difficulties in mathematics: Findings of a two-year longitudinal study.

The reading and mathematics growth of 180 children was examined over 4 points, spanning 2nd and 3rd grades.Initially, 4 achievement groups were identified: difficulties in mathematics but not in reading (MD only), difficulties in mathematics as well as in reading (MD-RD), difficulties in reading but not in mathematics (RD only), and normal achievement in mathematics and in reading.When IQ, income, ethnicity, and gender were held constant, the MD-only group grew at a faster rate in mathematics than did the MD-RD group.In reading, the RD-only and MD-RD groups grew at about the same rate.Reading abilities influence children's growth in mathematics, but mathematics abilities do not influence children's growth in reading.