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 activity is for students to explore sums within 10. Students pick their favorite sum as an entry point to the next activity in which students sort the sums into those they know and those they don’t yet know. In this activity, students may choose any sum within 10 that they like.
MLR8 Discussion Supports.
During group work, invite students to take turns sharing their responses. Ask students to restate what they heard using precise mathematical language and their own words. Display the sentence frame: “I heard you say . . .” Original speakers can agree or clarify for their partner.
Advances: Listening, Speaking
Launch
Groups of 4
Display the addition chart from the warm-up.
“You are going to choose your favorite sum from the addition chart. For example, my favorite sum is
\(8 + 2 = 10\)
because I like sums of 10.”
Activity
“Pick one or two sums that are your favorite. Explain why they are your favorite using drawings, numbers, or words.”
4 minutes: independent work time
“Share your favorite sums with the other students in your small group.”
4 minutes: small-group discussion
Monitor for students who wrote equations with addends of 0 or 1, equations with the same addend twice, or sums of 10.
Student Facing
Pick your favorite sum.
Write the equation: ________________________________
Show why it is your favorite using drawings, numbers, or words.
[IMG]
Student Response
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Activity Synthesis
Invite previously identified students to share their favorite sums.
“Why is this sum a favorite of yours?”


aligns: no