standard_description: Apply properties of operations as strategies to add and subtract. (Students need not use formal terms for these properties.) Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)
problem_activity: Stage 5: Cover (up to 20)
Required Preparation
Materials to Gather
Cups
Two-color counters
Materials to Copy
Blackline Masters
Shake and Spill Stage 4 and 5 Recording Sheet (G1 and 2)

Narrative
Students decide together how many counters, between 11–20, to use. Partner A closes their eyes while Partner B shakes, spills, and covers up the yellow counters with a cup. Partner A determines how many counters are under the cup and explains how they know. Both partners record the round. Switch roles and repeat.
Additional Information
Each group of 2 needs a cup and 20 two-color counters.


aligns: no