In this lesson, students interpret the unknown in a division situation as the number of groups. They consider draw pictures and division sentences to represent problems such as "My friend Cynthia is having a party. 18 people are coming. We know that 6 people can sit at each table; how many tables will we need?" They also relate finding the number of groups to counting by the divisor (for example, finding 15 ÷ 3 by counting by 3s and keeping track of the count).