## OVERVIEW

This lesson continues to discuss volume. Students will focus on finding the volume of irregular solid figures that are rectangular. They will break the figure into two separate rectangular prisms. Using their knowledge of volume, they will find the volume of each prism. Then they will add the two sums to determine the volume of the full figure. This introduces the concept of volume as additive.

You can explain how this works using several examples. Test students’ understanding by having them create their own rectangular prisms. They can then work with a partner to find the volume of each other’s figures. The lesson itself is very simple. You can be creative in how you present the concept of adding volumes. You may even want to use real-world examples and have them bring boxes from home.

### What Volume as Additive includes

This lesson builds on what the students have already learned about volume. After reviewing the volume formula, they can practice this new concept. The activity, practice, and homework worksheets provide extra practice for the students. They will be able to work with each other to further solidify their comprehension of the material.

ACTIVITY

Students will have to work with their classmates on the activity. This provides an opportunity for you to gauge who may need extra help. The students will create a prism with snap cubes. After that, they will have to draw their figure on the page. Next, they will take their prism to four different classmates. With each classmate, they will add the sum of both of their prisms. The sheet provides four boxes where they can record their answers.

PRACTICE

The practice worksheet illustrates that irregular figures can be divided in multiple ways. The sheet shows two sets of identical rectangular prisms. The students will divide each figure into two separate prisms in two different ways. Then they will find the volume of each to prove that they are the same.

HOMEWORK

The homework assignment provides further practice with volume. There are five total figures on the page. Each differs a little in presentation. Some look like snap cubes set up in a rectangular prism. On the other hand, some have only the outline with the measurements. This will test students’ ability to use different techniques to solve the problem.