Data are reported from the third individual interview conducted in 1979 as part of a 3-year study on addition and subtraction using verbal problem solving. From three schools in Wisconsin that used the Developing Mathematical Processes program, l50 first-grade children were individually administered six problem types (two solvable by addition and four solvable by subtraction) given under four conditions involving size of numbers and presence of manipulative materials. Answers were coded by model, correctness, and strategy. Individual student profiles are discussed first, followed by a summary of pupil response data. Several important aspects of the summary data are isolated for contrast and comment. Finally, some secondary analyses of combined data are given. Appendices contain sample problem tasks and individual student profiles. (MNS)