Under Taiwan curriculum reform teachers were encouraged to be curriculum developers. Developing a program for young children to do math problem posing (MPP) is a big challenge. An elementary school teacher created a MPP program for young children and the stages were four: Oral posing, Written Posing, Pose-and-solve own problem, and, Pose-and-Solve a friend’s problem. Three types (drawn, text, math expression) of tasks were used, and, two levels (high, and low) of math abilities were identified. The tasks were used in 24 lessons. Data collected were children’s posed problems, problem-solving test scores, children’s feedback sheet, and teacher’s journal and were analyzed using mixed methods. In the evaluation on MPP, children performed better in drawn and text than in math expression; and, the high group outperformed the low group. The class with MPP performed better than the class which did not use MPP. Instructional implications for developing an MPP program for young children were made.