Lesson objective: Solve multi-step measurement word problems using the standard algorithm for addition and subtration.

This lesson helps to build procedural skill with multi-digit addition and subtraction using the standard algorithm. Equations are used here because it supports students' work with modeling word problems in which there is an unknown quantity. This work develops students' understanding that we can use addition, subtraction, multiplication, and division to solve multi-step measurement problems.

Students engage in Mathematical Practice 6 (attend to precision) as they use mathematical symbols correctly. Students will include correct units in their writing and explanation of numerical quantities. They should be able to calculate with accuracy and efficiency using the standard algorithm for addition and subtraction.

**Key vocabulary:**

- algorithm
- equation
- regrouping

**Special materials needed:**