standard_description: Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.
problem_activity: Narrative
The purpose of this Choral Count is to invite students to practice counting backward by 1 and notice patterns in the count. When students describe repeated patterns they see using the language of place value, they look for and make use of the base-ten structure of numbers and connect it to the counting sequence (MP6, MP7, MP8).
Launch
“Count backward by 1, starting at 70.”
Record as students count.
Stop counting and recording at 20.
Activity
“What patterns do you see?”
1-2 minutes: quiet think time
Record responses.
Student Response
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Activity Synthesis
“Who can restate the pattern in different words?”


aligns: no