In this lesson, students revisit the relationship between multiplication and division to solidify their understanding of the meanings of division. Specifically, students recall that:

• We can think of multiplication as a way to quantify equal-size groups, and that we can find a product if we know the number of groups and the size of each group.
• We can interpret division as a way of finding a unknown factor, which can either be the number of groups, or the size of one group.

Students explore these ideas in the context of concrete situations and by using diagrams and equations to support their reasoning. The given quantities are small whole-numbers that are easy to work with mentally, allowing students to focus on the structure that relates the quantities. Understanding this structure will support students in reasoning about division of fractions.

As students represent division situations with diagrams and equations and interpret division equations in context, they practice reasoning abstractly and quantitatively (MP2).