standard_description: Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles. For example, arrange three copies of the same triangle so that the sum of the three angles appears to form a line, and give an argument in terms of transversals why this is so.
problem_activity: Stage 1: Factors
Required Preparation
Materials to Gather
Centimeter cubes
Materials to Copy
Blackline Masters
Find the Number Stage 1 Directions and Gameboard

Narrative
Students find all the factors for a given number. One player chooses a number on the gameboard (1–36) and they get that many points. The other player covers all the factors of that number. Their score is the sum of all the covered factors. Students take turns choosing the starting number. If a player chooses a number that doesn’t have any uncovered factors, they lose their next turn. When there are no numbers remaining with uncovered factors, the player with the most points wins.
Additional Information
Each group of 2 needs 36 centimeter cubes.


aligns: no