Lesson 12
School Supplies
Warmup: Notice and Wonder: School Supplies (10 minutes)
Narrative
Launch
 Groups of 2
 Display the image.
 “What do you notice? What do you wonder?”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 1 minute: partner discussion
 Share and record responses.
Student Facing
What do you notice?
What do you wonder?
Student Response
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Activity Synthesis
 "What math questions can you ask about this picture?"
 "We are going to work on lots of story problems about school supplies."
Activity 1: Not Enough Pencils (15 minutes)
Narrative
The purpose of this activity is for students to solve a Compare, Difference Unknown story problem using modified language. Students begin the activity by looking at the problem displayed, rather than in their books. They identify the important quantities before working on the problem, giving them an entry point for addressing the question, phrased negatively, of how many students will not have a pencil (MP1). When students open their books and work on the problem, they have access to connecting cubes or twocolor counters. In the lesson synthesis, students connect equations to different ways of solving the problem.
This activity uses MLR6 Three Reads. Advances: reading, listening, representing.
Advances: Representing, Conversing
Required Materials
Materials to Gather
Launch
 Groups of 2
 Give students access to connecting cubes or twocolor counters.
Activity
MLR6 Three Reads
 Display only the problem stem, without revealing the question(s).
 “We are going to read this problem three times.”
 1st Read: “There are 10 students at the table. There are 6 pencils.”
 “What is this story about?”
 1 minute: partner discussion
 Listen for and clarify any questions about the context.
 2nd Read: “There are 10 students at the table. There are 6 pencils.”
 “What are all the things we can count in this story?” (the number of students, the number of pencils)
 30 seconds: quiet think time
 1 minutes: partner discussion
 Share and record all quantities.
 Reveal the question(s).
 3rd Read: Read the entire problem, including question(s) aloud.
 “What are different ways we can solve this problem?” (I can use red connecting cubes for the students and blue for the pencils. I can draw circles for the students and lines for the pencils.)
 30 seconds: quiet think time
 1 minute: partner discussion
 "Solve the problem."
 3 minutes: independent work time
 “Share your thinking with your partner.”
 2 minutes: partner discussion
 Monitor for a student who represents counting up from 6 to 10 and one who represents subtracting 6 from 10.
Student Facing
There are 10 students at the table.
There are 6 pencils.
How many students won't get a pencil?
Show your thinking using drawings, numbers, or words.
Student Response
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Activity Synthesis
 Display previously identified student work.
 “How did they solve the problem?”
 Write an equation to match each method of solving.
Activity 2: Compare Problems (20 minutes)
Narrative
The purpose of this activity is for students to represent and solve Compare, Difference Unknown story problems. Students may use one of the following methods to find the difference or may come up with their own method.
Add on to the smaller set to make them equivalent.
(\(5 + \boxed{3} = 8\))
Match the sets and then count how many don’t have a partner. (\(8  5 =\boxed{3}\))
Show the total (8), color in the known amount (5), count the difference. (\(8 = 5 + \boxed{3}\) or \(8  5 =\boxed{3}\))
In the activity synthesis, students consider methods related to counting up and counting back.
Supports accessibility for: Language, VisualSpatial Processing
Required Materials
Materials to Gather
Launch
 Groups of 2
 Give students access to connecting cubes or twocolor counters.
Activity
 “You will solve more story problems about school supplies. Show your thinking using drawings, numbers, or words. Write an equation for each story problem.”
 6 minutes: independent work time
 3 minutes: partner discussion
 Monitor for a student who counted up and one who counted back for the problem about folders.
Student Facing

There are 9 markers in a bin.
There are 4 caps for the markers.
How many more caps are needed so that each marker has a cap?
Show your thinking using drawings, numbers, or words.Equation: ____________________________

There are 2 folders on the teacher's desk.
There are 9 folders on the supply table.
How many fewer folders are there on the desk than the table?
Show your thinking using drawings, numbers, or words.Equation: ________________________________

There are 5 dry erase boards at each table.
There are 8 markers at each table.
How many more markers are there than dry erase boards at each table?
Show your thinking using drawings, numbers, or words.Equation: ________________________________
Student Response
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Activity Synthesis
 Invite previously identified students to share.
 “How is their work the same? How is it different?” (They both use 2, 7 and 9. One uses addition and one uses subtraction. The answer is in a different place in each equation.)
 “Where is the answer to the question in each representation?” (When they added the answer was in the middle. When they subtracted it was at the end.)
 Add a box around the answer in each equation.
Lesson Synthesis
Lesson Synthesis
“Today we solved a new kind of story problem. How were these problems the same as the problems you solved in the past? How are they different?”(They were the same because we could add or subtract to solve them. They were different because we were comparing quantities instead of putting them together or taking them apart.)
Cooldown: Homework Papers (5 minutes)
CoolDown
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