The researcher want to investigate the continuous developmental performance of learning potential applying Multi-Stage Dynamic Assessment (MSDA) model to single-step word problem solving for first graders. Taking the between paried grouping experimental design to proceed study. The screened samples are 20 by pre-testing, and paired 10 to each group. One group is mediated by solving and transfer multi session dynamic assessment, the other take self-practice. Then two groups accept post-testing of solving and transfer tasks. Next the data are analyzed by adequate statistical methods . The simple gain scores of solving and transfer performance of treatment group is better than counterpart significantly, and pretesting performance of transfer is affected by posttesting performance of solving. The effectiveness of cumulative facilitation, potential discrimination for multi session dynamic assessment are found in treatment group. There is positive correlation existed between solving and transfer performance within treatment group also.