Hands-On with Rectangular Prisms!

Today, I wanted students to get a "real feel" for the volume of rectangular prisms. We learned the formula yesterday and I felt as if they understood how to complete the formula, but I wasn't convinced that they were convinced that there really were 36 cubic centimeters in the rectangular prism they calculated on paper ;)

Whenever possible, I like to bring in some hands-on activities so that students can grasp a concept and truly see how a formula, fractions, etc work. I find that in math it is very easy to do!

Materials Needed: 

• cardstock or construction paper
• marshmallows (sugar cubes work best, but no one sells them anymore!)
• glue

I first modeled EXACTLY what I wanted students to do with the materials. I have the luxury of a document camera, but you can also gather them on the floor/carpet to demonstrate. I made sure they set up the paper with both equations (V=B*h & V=l*w*h) and told them that they could decide whether to use a certain amount of marshmallows or build and then count as they built. The idea is to have them see that the total can really be found by using the formula, so they need to know what the total is before they complete the formulas. I built my rectangular prism using 18 marshmallows and we labeled the base and the height together and filled in the formula as a class. 

Next, I let students go to town on building their rectangular prism models. Some chose to make two models, others chose to make irregular prisms. This is a great activity that allows for differentiation and for me to see exactly what level each child is understanding this concept.