Solving Difference Problems: Wording Primes Coordination

In this study, we investigate the effect of problem text on solving three types of difference problems by first graders. COMPARE problems were significantly harder than EQUALIZE and WON'T GET problems. In terms of solution strategies, EQUALIZE problems were generally solved by an ADD-ON strategy; and the WON'T GET problems, by a MATCH strategy, which reflected the coordination of two mental number lines as the problem representation. No one strategy was used more often for the COMPARE problems, indicating that the COMPARE wording did not facilitate such coordination. These results suggest the coordination of mental number lines as the crucial component in solving difference problems.