Lesson 14
Compare with Addition and Subtraction
Warmup: True or False: Equal Sign (10 minutes)
Narrative
This is the second time students will do this instructional routine. The teacher should read aloud each equation. When students are more familiar with equations, they do not need to be read by the teacher.
Launch
 Display one statement.
 “Give me a signal when you know whether the statement is true and can explain how you know.”
 1 minute: quiet think time
Activity
 Share and record answers and strategy.
 Repeat with each equation.
Student Facing
Decide if each statement is true or false.
Be prepared to explain your reasoning.
 \(7 + 3 = 10\)
 \(10 = 7 + 3\)
 \(10 = 3 + 6\)
Student Response
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Activity Synthesis
 “How is 10 the same amount as \(7 + 3\)?” (When I add 7 and 3, the total is 10.)
 “If \(7 + 3 = 10\), and \(10 = 7 + 3\), would \(10 = 3 + 7\)?” (Yes, because 7 + 3 is the same amount as 10, and 10 is the same amount as \(3 + 7\).)
Activity 1: Is It Addition or Subtraction? (15 minutes)
Narrative
Required Materials
Materials to Gather
Launch
 Groups of 2
 Give students access to connecting cubes or twocolor counters.
 Display the image in the student book.
 “Tell a story about this picture.”
 1 minute: quiet think time
 2 minutes: partner discussion
 Share responses.
Activity
 Read the task statement.
 5 minutes: partner work time
 Encourage students to use the representation to make sense of both equations.
 Monitor for a group who uses the representation to explain the addition equation and one who explains the subtraction equation.
Student Facing
There are 8 glue sticks and 3 scissors at the art station.
How many fewer scissors are there than glue sticks?
Mai created a picture.
She is not sure which equation she should use to find the difference.
\(8  3 = \boxed{5}\)
\(3 + \boxed{5} = 8\)
Help her decide.
Show your thinking using drawings, numbers, or words.
Student Response
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Advancing Student Thinking
If students find the difference using only one operation, consider asking:
 "Can you explain how you found the difference between the number of glue sticks and scissors?"
 "Where in your drawing (objects) do you see the difference? How could you find that part of the representation by adding (subtracting)?"
Activity Synthesis
 “What are we trying to find out in this story problem?” (How many fewer scissors there are than glue sticks. The difference between the number of scissors and glue sticks.)
 Invite previously identified groups to share.
 “What is the same? What is different?” (3, 5, and 8 are in each equation. The numbers represent the same things in both. The 5 is boxed in both. One uses addition and the other uses subtraction. The boxed number is in a different place.)
Activity 2: Which Equation? (10 minutes)
Narrative
The purpose of this activity is for students to identify addition and subtraction equations that match Compare, Difference Unknown story problems. Students may not initially choose more than one equation for each problem, so this is the emphasis of the activity synthesis. Students continue to build their language of Compare problems and solidify the relationship between addition and subtraction.
Advances: Conversing, Reading
Supports accessibility for: Conceptual Processing, Attention
Required Materials
Materials to Gather
Launch
 Groups of 2
 Give students access to connecting cubes or twocolor counters.
Activity
 Read the task statement.
 3 minutes: independent work time
 2 minutes: partner discussion
 Monitor for a student who can show and explain how they chose which equation matches.
Student Facing

There are 5 red pillows and 3 blue pillows on the reading rug.
How many more red pillows are there than blue pillows?
Show your thinking using drawings, numbers, or words.Circle the equation that matches the problem.
\(5 + 3 = \boxed{\phantom{8}} \)
\(5  3 = \boxed{\phantom{2}}\)
\(5 + \boxed{\phantom{2}} = 3\)
\(3 + \boxed{\phantom{2}} = 5\)

There are 7 calculators on the table.
There are 8 math books.
How many more math books are there than calculators?
Show your thinking using drawings, numbers, or words.Circle the equation that matches the problem.
\(7 + \boxed{\phantom{1}} = 8\)
\(8  7 = \boxed{\phantom{1}}\)
\(7  8 = \boxed{\phantom{0}}\)
\(8 + \boxed{\phantom{1}} = 7\)

In Mr. Green’s class, 3 students have purple backpacks and 7 students have black backpacks.
How many more students have black backpacks than purple backpacks?
Show your thinking using drawings, numbers, or words.Circle the equation that matches the problem.
\(3 + 7 = \boxed{\phantom{10}}\)
\(3 + \boxed{\phantom{4}} = 7\)
\(7  \boxed{\phantom{4}} = 3\)
\(7 + \boxed{\phantom{1}} = 3\)
Student Response
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Activity Synthesis
 “How did you know which equation matched the problem about backpacks?" (I made a tower of 3 cubes to show the purple backpacks, and a tower of 7 cubes to show the black backpacks. Then I broke off the difference, which is 4. This matches 7  __ = 3 because the 4 shows the difference.)
 “Are there any other equations that represent this problem?” (Yes, 3 + ___ = 7 also matches. I started with 3 cubes, and added cubes until I got to 7. The amount I added was 4.)
 "There were two equations that match this problem. Check the other problems to see if there are any other equations that match."
Activity 3: Centers: Choice Time (15 minutes)
Narrative
The purpose of this activity is for students to choose from activities that offer practice telling and solving story problems and adding and subtracting within 10. Students choose from any stage of previously introduced centers.
 Capture Squares
 Math Stories
 Shake and Spill
Required Materials
Materials to Gather
Required Preparation
 Gather materials from previous centers:
 Capture Squares, Stage 1
 Math Stories, Stage 4
 Shake and Spill, Stages 3 and 4
Launch
 Groups of 2
 “Now you are going to choose from centers we have already learned.”
 Display the center choices in the student book.
 “Think about what you would like to do.”
 30 seconds: quiet think time
Activity
 Invite students to work at the center of their choice.
 10 minutes: center work time
Student Facing
Choose a center.
Capture Squares
Math Stories
Shake and Spill
Activity Synthesis
 “Tell your partner one thing they did that helped you during center time today.”
Lesson Synthesis
Lesson Synthesis
Display: In Mr. Green's class, 3 students have purple backpacks and 7 students have black backpacks. How many more students have black backpacks than purple backpacks?
\(3 + \boxed{4} = 7\) and \(7  3 = \boxed{4}\).
“Today we explained how different equations can match the same story. These are the equations that match this story. Why does the position of the answer change?” (Because one equation is addition and one is subtraction, because they used different methods to solve the problem, so the answer came in different places.)
“What does each number represent?”
Cooldown: Unit 2, Section C Checkpoint (0 minutes)
CoolDown
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