standard_description: Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.
problem_activity: Sort these shapes (cut out from
Polygons Template
) into groups. You may sort them any way you want and into as many groups as you want. Be prepared to explain how you sorted the shapes.
Sort them another way.


aligns: no