GRADE 1

Teacher Guide

UNIT 2

Made by Illustrative Mathematics.
This is a sample. Do not share it.

This book has rules about copying.
You can read more at the website shown.
Some pictures are free to use.
Other pictures belong to their owners.

Section C: Compare Story Problems

Standards

These are the math skills for this part.
Some skills come from before.
Some skills are new.
Some skills come later.

Goals

• Learn how adding and subtracting are connected.
• Solve problems that compare two groups.

We call these "Compare, Difference Unknown" problems.

What This Section Is About

In this part, kids solve compare problems.
These problems help kids see how adding and subtracting go together.

Compare problems are tricky.
They are not like "put together" problems.
They are not like "take apart" problems.
Compare problems show a relationship between two groups.

One part of the problem is missing.
That missing part is called the "difference."
The difference is not something you can see or touch.
The words in these problems can be tricky too.

First, kids remember problems from Kindergarten.
Those problems ask, "Are there enough?"
Kids use words like "more" and "fewer."

Next, kids solve new problems.
These ask, "How many more?"
These ask, "How many fewer?"
Kids find which group has more.
Kids find which group has fewer.
Kids find how many more or fewer.

Example:
There are 9 dry erase boards.
There are 6 markers.
Are there more boards or more markers?
How many more?

Kids use "matching" to help them think.
They match one item to another item.
This helps them see the bigger group.
This helps them see the smaller group.
The extra amount is the difference.

Example:
"How many more cubes does Clare have than Andre?"

Some kids count the extra cubes in Clare's tower.
Some kids add cubes to Andre's tower.
They make it match Clare's tower.
Some kids take away the matching cubes.
Then they count what is left in Clare's tower.

Kids connect this to problems from before.
The teacher writes down their ideas.
Kids look at addition problems.
Kids look at subtraction problems.
Both kinds of problems can show the same story.
This helps kids understand subtraction even better.

Section C Checkpoint

For the Teacher

Watch how kids solve these problems.
A checklist is in the assessment book.
Here is what to look for:

Compare Story Problems

• Solve Compare, Difference Unknown problems.
• Kids retell the story.
• Kids show the story with objects or drawings.
• Kids explain how their drawing matches the story.
• Kids give the right answer.
• Kids show how adding and subtracting connect.

Practice Problems

Problem 1
There are 7 dogs.
There are 5 toys.
Are there enough toys for each dog?
Show your thinking with drawings, numbers, or words.

Answer: No.

Problem 2
There are 10 bats in the cave.
There are 8 bats flying outside.
Are there fewer bats in the cave?
Or fewer bats flying outside?
How many fewer?
Show your thinking with drawings, numbers, or words.

Answer: 2 fewer bats.

Problem 3
Tyler sees hot air balloons at a show.
Here are their colors.

a. How many more blue balloons than orange balloons?
Show your thinking with drawings, numbers, or words.

b. How many fewer blue balloons than yellow balloons?
Show your thinking with drawings, numbers, or words.

Answer:
a. 3 more blue balloons.
b. 2 fewer blue balloons.

Problem 4
Jada's tower has 8 cubes.
Mai's tower has 2 cubes.
Show 2 ways to find how many more cubes Jada has.
Use objects, drawings, numbers, or words.

Answer:

• One way: add cubes to Mai's tower until it matches. Count the added cubes.
• Another way: draw Jada's tower. Cross off 2 cubes. Count what is left.

Problem 5
7 hedgehogs are underground.
4 hedgehogs are on the grass.
How many fewer hedgehogs are on the grass?
Show your thinking with drawings, numbers, or words.

Answer: 3 fewer hedgehogs.

Exploration Problem
8 stuffed animals are on the bed.
3 stuffed animals are on the floor.
Your teacher asks a question.
The answer is 5.
What could the question be?

Answer: How many more stuffed animals are on the bed than on the floor?

Exploration Problem
Find 2 groups of things at home or school.
Write a story comparing them.
Solve your problem.
Write a number sentence that matches your story.

Answer: My sister has 8 pillows. I have 5 pillows.
How many fewer pillows do I have?
I have 3 fewer pillows.

Unit 2, Lesson 11: Are There Enough?

Goals

• Tell about the difference between a big group and a small group.

Use words like "1 more" or "1 fewer."

• Explain ways to solve an "are there enough?" problem.

Student Goal

Let's figure out if there are enough.

Why We Are Learning This

Kids will show and solve "are there enough?" problems.
Kids will use "1 more" or "1 fewer" to compare things.

What This Lesson Is About

In Kindergarten, kids compared groups.
Kids asked, "Are there enough?"
Kids used "1 more" and "1 fewer."

Now kids remember these ideas.
This helps them get ready for harder compare problems.

Listen to how kids describe the groups.
Listen to how kids describe the difference.

Materials Needed

• 10-frames
• Connecting cubes
• Two-color counters

Lesson Timeline

• Warm-up: 10 minutes
• Activity 1: 20 minutes
• Activity 2: 20 minutes
• Wrap-up: 10 minutes

Warm-up: Act It Out - Art Project

10 minutes

This warm-up connects words to math.
It helps kids get ready for story problems later.

The Story:
Mai passes out crayons for an art project.
There are 8 students waiting for crayons.
Mai has 7 packs of crayons.
How can you act out this story?

Sample Answers:

• 8 students can pretend to wait for crayons.

Someone can pretend to be Mai.
Mai hands out 7 packs.

• Use counters for the 8 students.

Use blocks for the 7 packs of crayons.

How to Teach It

• Put kids in pairs.
• Show the story. Read it aloud.
• Ask: "What is this story about?"
• Give 30 seconds to think quietly.
• Kids share their ideas.
• Read the story again.
• Ask: "How can we act this out?"
• Give 30 seconds to think quietly.

Activity

• Kids talk with a partner.
• Give 1 minute to talk.
• Kids share ideas.
• Pick one way to act out the story together.
• Read the story together as a class.

Wrap-up Questions

• "What other ways could we show this problem?"

(Ideas: use cubes or counters. Draw a picture.)

Activity 1: Are There Enough?

20 minutes

In this activity, kids solve "are there enough?" problems.
Kids use drawings or objects that make sense to them.
Kids describe how the groups compare.

Watch how kids show "enough" or "not enough."
Listen for words about the bigger group.
Listen for words about the smaller group.
Listen for words about the difference.

At the end, kids describe things using "1 more" and "1 fewer."

Helping All Students

Ask kids to share a time in their own life.
A time they had to check if there was "enough" of something.

Materials Needed

• 10-frames
• Connecting cubes
• Two-color counters

Story Problems

Problem 1
There are 9 markers in a bin.
There are 4 caps for the markers.
Are there enough caps?
Show your thinking with drawings, numbers, or words.

Answer: No.
9 is much more than 4.

Problem 2
There are 9 students at the table.
There are 8 pencils.
Are there enough pencils for every student?
Show your thinking with drawings, numbers, or words.

Answer: No.

Problem 3
There are 6 students.
There are 8 chairs.
Are there enough chairs for every student?
Show your thinking with drawings, numbers, or words.