### Lesson plan

# Multiplication Models: Fractions and Whole Numbers

#### Learning Objectives

Students will be able to multiply a fraction by a whole number.

#### Introduction

*(5 minutes)*

- Show students an example of a multiplication model with two whole numbers, like
**3 x 5**. - Write the problem on the board and draw three circles to represent the three groups. Draw five dots in each circle.
- Write a repeated addition sentence to go with the picture (i.e.,
**5 + 5 + 5 = 15**). - Explain, "Three groups of five is 15, so
**3 x 5**is 15." - Tell students that today they are going to learn how to multiply a fraction by a whole number by using equal groups.

#### Explicit Instruction/Teacher modeling

*(10 minutes)*

- Using fraction strips or fraction bars, show students an example of a multiplication model with a fraction. Write the problem on the board (i.e.,
**3 x ⅕**). - Hold up one ⅕ bar and explain that
**3 x ⅕**is three groups with ⅕ in each group. - Draw three circles and place a ⅕ bar in each. Then write a repeated addition sentence to go with the drawing (i.e.,
**⅕ + ⅕ + ⅕**). - Ask, "How many fifths are there altogether?" The answer is three fifths. Take a student response and then explain that three times ⅕ is ⅗. (Write
**3 x ⅕ = ⅗**on the board.) - Show another example that does not use unit fractions, like
**3 x ⅖**. Demonstrate with fraction bars and write a repeated addition sentence to solve (i.e.,**⅖ + ⅖ + ⅖**). - Ask, "How many fifths are there altogether?" The answer is six fifths. Take a student response and then explain that three times ⅖ is 6/5. (Write
**3 x 2/5 = 6/5**on the board.)

#### Guided Practice

*(15 minutes)*

- Hand out a page of fraction strips and a sheet of construction paper to each student. (Note: in order to save time, have students cut only the fraction strips they need as they build models.)
- Write a problem on the board, like
**4 x ⅙**. - Instruct students to work with a partner to build a model. Remind students to draw circles on their construction paper to show the number of groups and glue their fraction strips to illustrate the problem. (Note: have students fold their paper in half and use just one half for their first model.)
- Have students write a repeated addition sentence and multiplication sentence to go with their model.
- Write a second problem on the board, like
**2 x ⅜**, and instruct students to build a model independently on the other half of their construction paper. Remind students to write a repeated addition sentence and multiplication sentence to go with their model. - Ask students to talk with a partner and come up with a rule to multiply a fraction times a whole number (i.e., multiply the whole number times the numerator—the denominator remains the same).
- Note: if students are unable to come up with the rule based on the first several examples, give a few more examples (i.e.,
**2 x ¼**,**2 x ¾**). Demonstrate with strips and guide students as needed to discover the algorithm. - Show students an example using the algorithm (i.e.,
**4 x 2/10 = 8/10**).

#### Independent working time

*(10 minutes)*

- Keep the examples from earlier in the lesson posted for student reference.
- Write four problems on the board and have students independently solve each, using the algorithm (i.e.,
**5 x 1/4**,**4 x ⅔**,**3 x 3/12**,**6 x 5/8**). - Hand out scratch paper or have students use math notebooks to solve.
- Circulate as students work and offer support as needed.
- Go over the problems as a class.

#### Differentiation

**Support:**

- Provide completed models and have students write a repeated addition sentence to go with the models.

**Enrichment:**

- Have students change improper fractions to mixed numbers when applicable.

#### Assessment

*(5 minutes)*

- Hand out a blank sticky note to each student.
- Write a problem on the board, like
**4 x 2/9**. Instruct students to solve on their sticky note. - Collect the problem as an exit ticket and check for understanding.

#### Review and closing

*(10 minutes)*

- Hand out one prepared sticky note to each student, with fractions written on each (e.g., eight students will have sticky notes that say ⅛, six students will have sticky notes that say ⅙, and so on so that every student has a sticky note).
- Instruct students to stick their fraction to their shirt and remain seated.
- Announce a multiplication problem, like
**4 x 2/8**, and have students (who are wearing the appropriate fraction) stand and group themselves together to make a human model. - Repeat with other problems, like
**2 x 3/6**, so that everyone has a chance to create a human model.