standard_description: Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
problem_activity: Determine if the statement below is always, sometimes, or never true. Explain your reasoning.
“To prove two triangles similar, you need to prove that two of the corresponding sides are proportional.”


aligns: no