Task# Maria's Marbles

Illustrative MathematicsVaries

This task includes problem types that represent the Compare contexts for addition and subtraction. There are three types of comparison problems - those with an unknown difference and two known numbers; those with a known difference and a bigger unknown number; and those with a known difference and smaller unknown number. Each of these problem types can be solved using addition or subtraction, although the language in specific problems tends to favor one approach over another. Please see the K, Counting and Cardinality; K-5, Operations and Algebraic Thinking Progressions Document for in-depth information about issues related to students' learning of these kinds of problems.