### Lesson plan

# Multiply Decimals

#### Learning Objectives

Students will be able to multiply decimals using the standard algorithm.

The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.

#### Introduction

*(5 minutes)*

- Review the standard algorithm for multiplication with two-digit whole numbers (i.e.,
**16 x 74**). - Tell students, "Today we are going to learn how to multiply decimals."

#### Explicit Instruction/Teacher modeling

*(10 minutes)*

- Write a decimal multiplication problem on the board (i.e.,
**0.24 x 0.97**). - Explain that when multiplying decimals, you can ignore the decimal place and multiply using the standard algorithm normally.
- Demonstrate by multiplying the two numbers (the product is
**2,328**). - Point out that both factors are less than one, and say, "What is one times one? If both factors are less than one, our product should be less than one."
- Point out the answer you've written on the board (
**2,328**) and ask, "Is this a logical answer?" - Explain that even though you can multiply normally, as you would with whole numbers, you must add the decimal back into the product in the correct place.
- Tell students that the product will have the same number of digits behind the decimal place as both factors combined.
- Count the digits behind the decimal in the factors (4). Then add the decimal into the product with the same number of digits behind it (i.e., 0.2328).

#### Guided practise

*(15 minutes)*

- Guide students through another example (e.g.,
**7.96 x 0.4**). - Give students a problem to solve with a partner (e.g.,
**0.37 x 5.2**). - Give students a "try it" problem to solve independently (e.g.,
**0.61 x 1.85**). Circulate and offer support as needed. Then go over the problem as a class.

#### Independent working time

*(15 minutes)*

- Hand out the Multiplying Decimals worksheet and go over the example with the class.
- Instruct students to complete the worksheet independently.
- Circulate and offer support as needed.
- Go over the worksheet with the class.

#### Differentiation

**Support:**

- Provide additional examples before assigning independent work.
- Have students highlight the numbers after the decimal place in the factors and in the product to make sure the decimal is in the correct place.

**Enrichment:**

- Have students solve challenge problems with additional place values after the decimal (i.e.,
**84.0134 x 2.17**).

#### Assessment

*(5 minutes)*

- Hand out a piece of scratch paper to each student.
- Write a decimal multiplication problem on the board (e.g.,
**2.38 x 0.91**) and have students solve. - Collect student work as an exit ticket and check for understanding.

#### Review and closing

*(10 minutes)*

- Teach your students the "Multiplying Decimals Song" (see related media).