standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Stage 1: Add Ones
Required Preparation
Materials to Gather
Connecting cubes in towers of 10 and singles
Number cards 0–10
Materials to Copy
Blackline Masters
Target Numbers Stage 1 Recording Sheet

Narrative
Before playing, students remove the cards that show 0 and 10 and set them aside.
Students add a one-digit number to a two-digit number with composing a ten in order to get as close to 95 as possible. Students start their first equation with 55 and turn over a number card and add it to their starting number for the round. The sum becomes the first addend in the next round. The player who gets closest to 95 in 6 rounds, without going over, is the winner.


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