standard_description: Derive the formula A = 1/2 ab sin(C) for the area of a triangle by drawing an auxiliary line from a vertex perpendicular to the opposite side.
problem_activity: Stage 2: Subtract 1 or 2
Required Preparation
Materials to Gather
Number cards 0–10
Two-color counters
Materials to Copy
Blackline Masters
Five in a Row Addition and Subtraction Stages 1 and 2 Gameboard

Narrative
Students choose a number card 0-10 and choose to subtract 1 or 2 from the number on their card and then place their counter on the difference.
Variation:
Students can choose to add or subtract 1 or 2.
Additional Information
Each group of 2 needs 25 counters.


aligns: no