The purpose of this Number Talk is to elicit the strategies and understandings that students have for adding three 1-digit numbers within 20. When students look for ways to decompose addends to make a ten with another addend, and add the remaining addends to find the sum, they look for and make use of the structure of numbers and properties of operations (MP7).
Launch
Display one expression.
“Give me a signal when you have an answer and can explain how you got it.”
1 minute: quiet think time
Activity
Record answers and strategies.
Keep expressions and work displayed.
Repeat with each expression.
Student Task Statement
Find the value of each expression mentally.
Student Response
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Advancing Student Thinking
Activity Synthesis
“Who can restate _____'s reasoning in a different way?”
“Does anyone have the same strategy but explains it differently?”
“Did anyone approach the problem in a different way?”
Activity 1
20 mins
Revisit Match Mine—Solid Shapes
Standards Alignment
Building On
Addressing
1.G.A.2
Compose two-dimensional shapes (rectangles, squares, trapezoids, triangles, half-circles, and quarter-circles) or three-dimensional shapes (cubes, right rectangular prisms, right circular cones, and right circular cylinders) to create a composite shape, and compose new shapes from the composite shape.Students do not need to learn formal names such as “right rectangular prism.”
The purpose of this activity is for students to revisit Stage 2 of the Match Mine center introduced in kindergarten. Students put solid shapes together to make a larger object, without letting their partner see. They then describe the object to their partner, who tries to match it. In order to make matching objects, each partner needs a matching set of solid shapes.
Launch
Groups of 2
Give each group matching sets of solid shapes and something to hide their work, like a folder.
“We are going to learn a new way to play Match Mine, which is a center that was introduced in kindergarten. Let’s play one round together. You all can be my partner.”
Without showing students, put four shapes together to make an object.
“One person starts by putting 4 shapes together to build something new. They hide their object so their partner can’t see it. Then they describe their object to their partner, who tries to match it. I will describe my object and you can try to match it.”
Describe your object and allow students to try to match it with the shapes.
Discuss what you said that helped students match the object, and what you said that might not have helped.
Activity
“Now you will play with your partner.”
10 minutes: partner work time
Student Task Statement
None
Student Response
None
Advancing Student Thinking
Activity Synthesis
“What did your partner do or say to make it easier to match their object?” (My partner used only 4 blocks, so it was easy to match their object. My partner told me when to put a block on top of another block, or next to it.)
The purpose of this activity is for students to choose from activities that offer practice adding and subtracting or working with shapes. Students choose from previously introduced stages of these centers:
Picture Books
How Are They the Same?
Capture Squares
Launch
Groups of 2
“Now we 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 first.”
30 seconds: quiet think time
Activity
Invite students to work at the center of their choice.
8 minutes: center work time
“Choose what you would like to do next.”
8 minutes: center work time
Student Task Statement
Choose a center.
Picture Books
How Are They the Same?
Capture Squares
Student Response
None
Advancing Student Thinking
Activity Synthesis
“What did the centers you worked on today help you practice?”
Lesson Synthesis
“How did you and your partner work together during centers? What went well? What can we continue to work on?”
Standards Alignment
Building On
Addressing
1.OA.C.6
Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., ); decomposing a number leading to a ten (e.g., ); using the relationship between addition and subtraction (e.g., knowing that , one knows ); and creating equivalent but easier or known sums (e.g., adding by creating the known equivalent ).