For example, in the lesson on population growth, during the Explanation phase, I have students share their answers to the questions described in the task (see Appendix A). As they share their answers, we discuss how they arrived at the answers. They were supposed to have graphed the growth of their assigned families. We discuss the patterns of growth represented in the graphs and try to figure out the factors influencing growth from those patterns and the information provided about the families in the task description. Connections between the factors (biological) and the growth pattern (mathematical) become evident during these discussions.