standard_description: Fluently add and subtract within 20 using mental strategies. (See standard 1.OA.6 for a list of mental strategies.) By end of Grade 2, know from memory all sums of two one-digit numbers.
problem_activity: Narrative
The purpose of this warm-up is to allow students to connect language to mathematical representation, which will be useful when students need to compare quantities and numbers in later activities. In the synthesis, students have the opportunity to practice using the language “more” to compare quantities.
This warm-up gives students opportunities to make sense of a problem by acting it out first before thinking about how to solve the problem (MP1).
Launch
Groups of 2
Display and read the story.
“What is the story about?”
30 seconds: quiet think time
Share responses.
Read the story again.
“How can you act out this story?”
30 seconds: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share responses.
Choose a way to represent the story as a class.
Read the story together.
Student Facing
Lin and her brother are setting the table for dinner.
Lin put 8 cups on the table.
Her brother put 6 plates on the table.
Did Lin or her brother put more things on the table?
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Student Response
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Activity Synthesis
“Did Lin or her brother put more things on the table? How do you know?” (Lin put more things on the table. When we acted it out, there were 2 plates that did not have any cups, so there were more plates. 8 is more than 6.)
“Tell your partner about 8 and 6 using ‘more.’” (8 is more than 6.)
“8 plates is more than 6 cups. 8 is more than 6.”


aligns: no