Lesson 1
Add and Subtract Within 10
Warmup: What Do You Know About Math? (15 minutes)
Narrative
The purpose of this activity is to elicit ideas students have about doing math. Students learn the What Do You Know _____? routine which will be used throughout the year. This routine provides an opportunity for all students to contribute to the conversation and for the teacher to listen to what knowledge students already have. Since this is the first warmup of the year, we allocated 15 minutes, instead of 10, to establish the structure of a routine.
For all of the routines, consider establishing a small, discreet hand signal that students can display to indicate they have an answer they can support with reasoning. This signal could be a thumbsup, a certain number of fingers that tells the number of responses they have, or another subtle signal. This is a quick way to see if students have had enough time to think about the problem. It also keeps students from being distracted or rushed by hands being raised around the class.
Launch
 Display the question.
 “What do you know about math?”
 1 minute: quiet think time
Activity
 Record responses.
Student Facing
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 “Today, you will get to do math in different ways.”
Activity 1: Check It Off: Add or Subtract within 10 (20 minutes)
Narrative
The purpose of this activity is for students to demonstrate methods they have for addition and subtraction within 10. In this activity, students draw 2 cards and consider how they could add or subtract the numbers to create a value that matches one of the target numbers (0–10). Listen for the ways students think about how to find the value of sums and differences, including any sums and differences they know from memory, and how they share their thinking with their partner. If students disagree about the value of a sum or difference, encourage them to discuss their reasoning and reach an agreement (MP3).
Students may write subtraction expressions that do not match their computation (for example, students write \(2  4\) instead of \(4  2\)). Ask them to use counters or cubes to represent the subtraction. Highlight that they started with 4 and took away 2 and ask them to connect this action to the expression. To stay mathematically consistent with what students will learn in later grades about operations with rational numbers, avoid language that suggests students can only subtract a smaller number from a larger number.
Advances: Speaking, Listening, Representing
Supports accessibility for: Conceptual Processing, VisualSpatial Processing
Required Materials
Required Preparation
 Create a set of number cards for each group of 2.
 The number cards will be used in upcoming lessons and thoughout the year. Consider copying the cards on cardstock or laminating them for future use.
 Create the math community poster for display in the lesson synthesis.
Launch
 Groups of 2
 Give each group a set of number cards.
 Give students access to connecting cubes or counters.
 “We are going to play Check It Off: Add or Subtract within 10. The goal is to be the first person to write an expression for each number.”
 “I’m going to pick two cards. (Show 10 and 7.) I have to decide whether I want to add or subtract. I don’t want a value greater than 10, so I’m going to subtract.”
 Write \(10  7\).
 “What is the value of the difference?”
 30 seconds: quiet think time
 Share responses.
 “I record the expression I made on my recording sheet next to the value of the difference and check off the number. Now it’s my partner’s turn.“
 “Take turns picking cards, making an addition or subtraction expression, finding the value of the sum or difference, and showing your partner how you know.”
 “If you run out of cards before someone checks off all the numbers, shuffle them and start again.“
Activity
 10–15 minutes: partner work time
Student Facing
 Pick 2 cards and find the value of the sum or difference.
 Check off the number you found and write the expression.
 The person who checks off the most numbers wins.
Found it!  Expression  

0  
1  
2  
3  
4  
5  
6  
7  
8  
9  
10 
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 “Did you write any expressions that matched the same value? What number was it? What were the expressions?"
 "Were there any values that you and your partner did not find? What are some expressions that could match these numbers?"
 If needed ask,
 “What expressions did you get for 5?” (Answers will vary. Sample response: I found \(10  5\) and \(3 + 2\).)
 “What expressions did you get for 0?” (Answers will vary. Sample response: I found \(9  9\) and \(0 + 0\).)
 “What expressions did you get for 10?” (Answers will vary. Sample response: I found \(3 + 7\) and \(10 + 0\).)
Activity 2: What’s the Value? (10 minutes)
Narrative
The purpose of the activity is for students to practice finding the value of sums and differences within 10. Students also identify addition expressions that have a value of 10. Students will work more with sums of 10 in the next lesson. This activity provides an opportunity to observe how students find sums and differences within 10, including those they know from memory.
Required Materials
Materials to Gather
Launch
 Groups of 2
 Give students access to connecting cubes or counters.
 Read task statement.
Activity
 6 minutes: independent work time
 “Share your thinking and your answers with a partner.”
 1 minute: partner discussion
Student Facing

Match each expression to the value of the sum or difference.
 \(5 + 3\)
 \(3  1\)
 \(10  1\)
 \(4 + 5\)
 \(6 + 3\)
 \(6  5\)
 \(1 + 6\)
 \(9  5\)
 \(8  5\)
 \(3 + 6\)
 9
 3
 8
 7
 1
 4
 2
 Circle all the addition expressions that have a value of 10.
 What patterns do you see in the numbers in the expressions that have a value of 10?
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 Ask students to share answers to problem 3.
 Record responses.
Lesson Synthesis
Lesson Synthesis
“Today, you played a math game and added and subtracted within 10. We are going to make a chart to describe what you do and I do in our mathematical community.”
Display math community poster.
“What does it look and sound like to do math together as a mathematical community?” (We talked to each other and to the teacher. We had some quiet time to think. We shared our ideas. We thought about the math ideas and words we knew. You were writing down our answers. You were waiting until we gave the answers.)
Share and record responses.
Cooldown: Sums and Differences (5 minutes)
CoolDown
For access, consult one of our IM Certified Partners.