standard_description: Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.
problem_activity: Stage 1: Add and Subtract within 10
Required Preparation
Materials to Copy
Blackline Masters
Compare Stage 1 Addition Cards to 10
Compare Stage 1 Subtraction Cards to 10

Narrative
Students use cards with addition and subtraction expressions within 10.


aligns: no