standard_description: Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a drawing or equation (e.g., 18 = 10 + 8); understand that these numbers are composed of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.
problem_activity: Narrative
The purpose of this activity is for students to use their knowledge of the number sequence to find the number that matches clues with one more and one less. Numbers 1–20 are displayed around the room. The numbers may be displayed in order, or the sequence of numbers can be mixed up for more of a challenge. The cards with number clues are included as a blackline master; one example is included in the student-facing task statement. Consider developing a signal, such as ringing a bell, so that students know when to move around the classroom. In the activity synthesis, students consider why there can be different clues that match a given number.
Engagement: Internalize Self-Regulation.
Provide students an opportunity to self-assess and reflect on the number clue and if that number clue matches the number they will stand by. For example, students can choral count together to check that the number 9 is 1 less than 10.
Supports accessibility for: Memory, Conceptual Processing
Required Materials
Materials to Copy
Number Clues
Required Preparation
Each group of 2 needs one card from the blackline master.
Display large numbers 1 to 20 around the room. The numbers may be displayed in order, or the sequence of numbers can be mixed up for more of a challenge.
Launch
Groups of 2
Display number cards 0–20 around the room, in order or mixed up.
Give each group of students a card.
“On your card there are some clues. Each clue says ‘1 more than _____’ or ‘1 less than _____.’”
“Look at your first clue. Decide with your partner which number matches the clue. Then look around the room and find that number. When I give the signal, walk over to that number.”
Activity
2 minutes: partner work time
“Discuss with the other people at your number. Did you have the same clue? Are you all at the correct number? How do you know?”
2 minutes: small-group work time
Repeat the steps with the rest of the clues.
During the final round, monitor for a group that notices there are 2 different clues that match the number and discuss why they both match.
Student Response
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Activity Synthesis
Invite previously identified students to share what they noticed during the last round of number clues.
“‘1 more than 15’ and ‘1 less than 17’ are both clues to 16.”
“What are two different clues that could match the number 12?”


aligns: no