### Lesson plan

# Multiplication: Solving for Unknown Factors

#### Learning Objectives

Students will be able to solve for the unknown factor in multiplication problems.

#### Introduction

*(10 minutes)*

- Tell your students that today they are going to learn strategies for solving for the unknown factor involving multiplication problems.
- Ask your students to share division strategies they know.
- As the students share, list the strategies on the board. Your students might offer suggestions such as repeated subtraction or arrays.

#### Explicit Instruction/Teacher modeling

*(15 minutes)*

- Write a few multiplication problems on the board with an unknown factor. For example,
*6 x ____ = 36*. - Have your students rewrite the problem as a division problem, as follows:
*36 ÷ 6 = _____*. - Ask your students to choose an effective division strategy that they know.
- Solve the problem using repeated subtraction:
*36-6=30-6=24-6=18-6=12-6=6-6=0*. - Then, show your students how to solve the problem using arrays or grouping: XXXXXX XXXXXX XXXXXX XXXXXX XXXXXX XXXXXX
- Explain to your students how you got the answer
*6*.

#### Guided Practice

*(15 minutes)*

- Have your students solve
*_____ X 5 = 40*using what they think is the most efficient strategy. - Ask for volunteers to raise their hands and share with the class the steps to solve the problem.
- As the problem is being solved aloud, write down the steps on the whiteboard.
- When the problem is done, review it with the class for accuracy.

#### Independent working time

*(15 minutes)*

- Give the students the Solve the Unknown Factor worksheet to complete.

#### Differentiation

**Enrichment:**Have your students skip the division step on their papers to solve the multiplication problems. Encourage them to memorize multiplication facts to quickly solve problems.**Support:**Give your students simpler problems to solve, such as*3 x ___ = 12*. Use manipulatives to help show grouping and arrays.

#### Assessment

*(10 minutes)*

- Walk around and observe the students as they work on completing the assignment.
- Monitor the students as they work, making sure that the problems are done correctly.

#### Review and closing

*(10 minutes)*

- Ask for volunteers to share their answers and justification.
- As the problems are reviewed in front of the class, have the students check their answers for accuracy.