Traditional styles of teaching would have children doing many examples of their times tables. This, however, does not encourage them to use active problem solving techniques and, thus, does not require much thinking. By incorporating problem solving, students become more involved with the problem as they have to find the information from the problem and use that to solve a question.
It was found to be beneficial to structure a lesson around one to three problems as it develops and increases multiplicative thinking in students because time can be spent on discussing strategies, models and reasoning. (Van de Walle and Folk 128).
Van de Walle, John, and Folk, Sandra. Elementary and Middle School Mathematics - Teaching Developmentally. Canadian ed. Pearson Education Canada, 2005.