# Lesson 1

Equal Groups of Unit Fractions

## Warm-up: How Many Do You See: Oranges (10 minutes)

### Narrative

The purpose of this How Many Do You See is to elicit ideas about equal groups of fractional amounts and to prepare students reason about multiplication of a whole number and a fraction. Students may describe the oranges with a whole number without units or without specifying “halves” (for instance, they may say “5”). If this happens, consider asking them to clarify whether they mean “5 oranges” or another amount.

### Launch

• Groups of 2
• “How many do you see? How do you see them?”
• Display the image.
• 1 minute: quiet think time

### Activity

• 1 minute: partner discussion
• Record responses.

### Student Facing

How many do you see? How do you see them?

### Activity Synthesis

• “How might you describe this image to a friend?” (There are 5 plates with $$\frac{1}{2}$$ orange on each plate.)
• “How many groups do you see?” (I see 5 plates or 5 groups.)
• “Besides describing the image in words, how else might you represent the quantity in this image?” (I might write $$\frac{1}{2}$$ five times, or write an expression with five $$\frac{1}{2}$$s being added together. I might write “5 times $$\frac{1}{2}$$.”)
• “We'll look at some other situations involving groups and fractional amounts in this lesson.”

## Activity 1: Crackers, Kiwis, and More (20 minutes)

### Narrative

The purpose of this activity is for students to interpret situations involving equal groups of a fractional amount and to connect such situations to multiplication of a whole number by a fraction (MP2).

Students write expressions to represent the number of groups and the size of each group. They reason about the quantity in each situation in any way that makes sense to them. Although images of the food items are given, students may choose to create other diagrams, such as equal-group diagrams used in grade 3, when they learned to multiply whole numbers. This activity enables the teacher to see the representations toward which students gravitate.

Focus the discussions on connecting equal groups with fractions and those with whole numbers.

Representation: Access for Perception. Use pictures (or actual crackers, if possible) to represent the situation. Ask students to identify correspondences between this concrete representation and the diagrams they create or see.
Supports accessibility for: Conceptual Processing, Visual-Spatial Processing

### Launch

• Groups of 2
• “What are some of your favorite snacks?”
• Share responses.
• “What are some snacks that you might break into smaller pieces rather than eating them whole?”
• 1 minutes: partner discussion
• “Let's look at some food items that we might eat whole or cut or break up into smaller pieces.”

### Activity

• “Take a few quiet minutes to think about the first set of problems about crackers. Then, discuss your thinking with your partner.”
• 4 minutes: independent work time
• 2 minutes: partner discussion
• Pause for a whole-class discussion. Invite students to share their responses.
• If no students mention that there are equal groups, ask them to make some observations about the size of the groups in each image.
• Discuss the expressions students wrote:
• “What expression did you write to represent the crackers in Image A? Why?” ($$6 \times 4$$, because there are 6 groups of 4 full crackers.)
• “What about the crackers in Image B? Why?” ($$6 \times \frac{1}{4}$$, because there are 6 groups of $$\frac{1}{4}$$ of a cracker.)
• Ask students to complete the remaining problems.
• 5 minutes: independent or partner work time
• Monitor for students who reason about the quantities in terms of “_____ groups of _____” to help them write expressions.

### Student Facing

1. Here are images of some crackers.

1. How are the crackers in image A like those in B?
2. How are they different?
3. How many crackers are in each image?
4. Write an expression to represent the crackers in each image.
2. Here are more images and descriptions of food items. For each, write a multiplication expression to represent the quantity. Then, answer the question.

1. Clare has 3 baskets. She put 4 eggs into each basket. How many eggs did she put in baskets?

2. Diego has 5 plates. He put $$\frac12$$ of a kiwi fruit on each plate. How many kiwis did he put on plates?
3. Priya prepared 7 plates with $$\frac18$$ of a pie on each. How much pie did she put on plates?
4. Noah scooped $$\frac13$$ cup of brown rice 8 times. How many cups of brown rice did he scoop?

### Student Response

If students are unsure how to name the quantity in the image, consider asking: ”How would you describe the amount of the slice of pie on one plate? How would you describe two of the same slices? Three of the same slices?”

### Activity Synthesis

• Select previously identified students to share their expressions and how they reasoned about the amount of food in each image. Record their expressions and supporting diagrams, if any, for all to see.
• If students write addition expressions to represent the quantities, ask if there are other expressions that could be used to describe the equal groups.
• “How is the quantity in Clare's situation different than those in other situations?” (It involves whole numbers of items. Others involve fractional amounts.)
• “How is the expression you wrote for the eggs different than other expressions?” (It shows two whole numbers being multiplied. The others show a whole number and a fraction.)

## Activity 2: What Could It Mean? (15 minutes)

### Narrative

In this activity, students start with given multiplication expressions and consider situations or diagrams that they could represent. Situating the expressions in context encourages students to think of the whole number in the expression as the number of groups and the fractional amount as the size of each group, which helps them reason about the value of the expression. When students make explicit connections between multiplication situations, expressions, and drawings they reason abstractly and quantitatively (MP2).

Allow students to use fraction strips, fraction blocks, or other manipulatives that show fractional amounts to support their reasoning.

MLR8 Discussion Supports. Synthesis: Provide students with the opportunity to rehearse what they will say with a partner before they share with the whole class.

### Launch

• Groups of 2
• 1 minute: partner discussion

### Activity

• “Think of a story that can be represented by the expression. Then, create a drawing or diagram, and find the value of the expression.”
• “If you have extra time you can work on both problems.”
• 7–8 minutes: independent work time
• “Be sure to say what the value of the expression means in your story.”

### Student Facing

For each expression:

• Write a story that the expression could represent. The story should be about a situation with equal groups.
• Create a drawing to represent the situation.
• Find the value of the expression. What does this number mean in your story?
1. $$8 \times \frac{1}{2}$$

2. $$7 \times \frac {1}{5}$$

### Activity Synthesis

• Invite students to share their responses. Display their drawings or visual representations for all to see.
• “How did you decide what the numbers in each expression represent in your story?” (It made sense for the whole numbers to represent how many groups there are and the fractions to represent what is in each group.)
• “How did you show the whole number and the fraction in your drawing?” (I drew as many circles as the whole number to show the groups. I drew parts of objects or wrote numbers in each circle to show the fraction.)

## Lesson Synthesis

### Lesson Synthesis

“Today we looked at different situations that involved equal-size groups and a fractional amount in each group. We thought about how to find the total amount in each situation.”

“How did we represent these situations?” (We wrote expressions and used drawings or pictures to show the equal groups.)

“What kind of expressions did we write?” (Multiplication expressions with a whole number and a fraction in each)

“What strategies did we use to find the total amount in each situation?” (We counted the number of fractional parts in the drawings. We counted how many parts made 1 whole and saw how many extra fractional parts there were.)