Students will use the commutative property with counting strategies to solve problems with find change unknown (including add to and take from) and addend unknown (including put together and take apart) using objects and pictures. Chart paper for student work Cubes, counters, etc. Sets of change unknown story problems, join and separate. As you plan, consider the variability of learners in your class and make adaptations as necessary. By the end of this lesson students will know and be able to 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.