In previous lessons, students made sense of and matched equations to different story problems. In the last lesson, they wrote equations to match story problems or to show how they solved a story problem. In this lesson, students represent and solve story problems that can be represented as an equation with unknown addend. They are encouraged to write an equation with a symbol for the answer to the question, but they are not required to. Students may write a second equation using the relationship between addition and subtraction, the commutative property, or the meaning of the equal sign.

How do you see your students demonstrating an understanding of the relationship between addition and subtraction? Are students working flexibly with addition and subtraction in order to find unknown values?