standard_description: Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).
problem_activity: Narrative
The purpose of this activity is for students to choose from activities that offer practice working with two-digit numbers. Students choose from any stage of previously introduced centers.
Write Numbers
Grab and Count
Five in a Row
Required Materials
Materials to Gather
Materials from previous centers
Required Preparation
Gather materials from previous centers:
Write Numbers, Stages 1 and 2
Grab and count, Stage 2
Five in a Row, Stages 1–3
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.
Write Numbers
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Grab and Count
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Five in a Row
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Activity Synthesis
“Mai is playing Grab and Count with her partner. She organized her cubes into 4 towers of 10 and 3 ones. Her partner organized her cubes into 2 towers of 10. How many cubes do they have together?”


aligns: yes