Volume and Surface Area – with boxes

By: Mary Kienstra on: April 11, 2015  in: math engagement, median, volume

When teaching volume and surface area, there is no better way than to get out the rectangular prisms (a.k.a. boxes) and let the students figure it out.  On days like this, I like to get out of their way and just watch it unfold.

Last year I realized that volume and surface area cannot be explored only on worksheets.  Fifth graders still need concrete models.  They need to touch, feel, manipulate, and measure in order to build their understanding of concepts.  So once again, this year I brought in a collection of boxes.

Before the kids started measuring, we discussed as a group the definitions of volume and surface area.  They have experience with volume from prior years, but surface area is a new concept.  Area is familiar, so once we defined surface area as the sum or the area of all the faces of the rectangular prism, they understood it clearly.

Fifth graders need to touch and measure to find volume and surface area.

The kids were divided into groups where they had to decide which units to use: inches or centimeters.  The only requirement was that they all had to use the same measurement system.  The discussion that followed included such ideas as whether it would be easier to calculate with decimals (centimeters) or fractions (inches), and  which would be more accurate.  This was a perfect way to work in the math practice standards.

A collection of boxes helps kids understand these concepts.

Once they decided that they would use centimeters, they set out to work measuring.  This was engaging work as they measured, discussed, and calculated.  I heard comments reminding each other about how to find volume and conjectures about how to calculate surface area.  My students were collaborating and discussing, helping each other to understand these concepts.

This lesson reminds me that any time you can give kids a real experience instead of a worksheet, do it!  There is no substitute for using rectangular prisms (a.k.a. boxes) to study volume and surface area.

What kinds of experiences do you give your students to help them understand math concepts?