Use Question 10 in the Student Guide to summarize the lesson. In this problem, students invent situations to represent division problems. This helps students make meaning of division and provides a context for checking the reasonableness of their answers. Students then write each division problem as a multiplication sentence and use related number sentences to help them solve the problem.
After student pairs complete the problems, select one or two problems to discuss with the whole class. Ask students to share their stories for the problem, their solutions, and their reasoning. Have several students share different methods for solving the same problem. This will expose students to varied and flexible ways to divide mentally, and it may uncover simpler, more efficient methods for students who are struggling with using mental math to divide.
- Who would like to share their story for 112 ÷ 3? (Stories will vary. Possible response: Mrs. Haddad has 112 small boxes of Chocos. She wants to pack them into 3 larger cartons for shipping, distributing them equally among the cartons. How many small Choco boxes will be packed into each carton?)
- Write 112 ÷ 3 as a multiplication problem with a missing factor. (3 × ? = 112)
- What are the related number sentences that helped you solve the problem? (Possible response: I thought of 3 × 3 = 9, 3 × 30 = 90, 3 × 4 = 12, 3 × 40 = 120.)
- Explain how you solved the problem. (Possible response: I thought 3 times what number will make 112. I knew that if 3 × 30 = 90 and 3 × 40 = 120, that the number would be in between 30 and 40, but closer to 40 since 112 is closer to 120 than it is to 90. First I tried 36 × 3 by adding 36 + 36 + 36 and got 108. That meant Mrs. Haddad could fill each of the 3 cartons with 36 little Choco boxes but still had 4 little boxes left to pack. I added 1 more Choco box to each cartons. Each carton held 37 and there was 1 little Choco box left over.)
- Let's all solve this problem to see if [student's name]'s answer is reasonable.
- Did anyone solve this problem a different way? Show us your method.
- Which method was easier or more efficient for you to use? Why?
