One topic that I believe is too often rushed through, whether in pre-algebra or geometry, is the surface area of three dimensional objects. Because it is often seen as an “easy” topic where students are expected to simply “plug the numbers into the formula,” it can be easy to say, “Here’s the formula, GO.” And while this may work for some students, especially students who have a strong foundation in geometry vocabulary and a strong understanding of area in general, simply “plugging numbers into the formula” doesn’t come as easily to others. This hands-on investigation for exploring surface area of prisms and cylinders will help students understand surface area in a conceptual way, and requires NO memorizing of formulas!
One reason the surface area formulas cause problems for students is that they don’t know what all the variables mean. For example, when I taught surface area and volume to a group of eighth graders, the majority of whom did not speak English as their first language, all the symbols in the formulas did not make sense to them.
It can also be confusing for students (even if they speak English!) to understand the ‘B’ in surface area formulas (standing for ‘area of the base‘) because they want to input a single number rather than finding the area of the base.
Exploring Surface Area of Prisms and Cylinders:
Because of all the ways the technical formulas can be confusing for students, I prefer to teach students based solely on the understanding that surface area simply means the sum of the areas of all surfaces.
This allows students to think logically through solving any surface area problem, rather than relying on memorizing a formula or trying to correctly “plug in the numbers.”
This also helps minimize careless mistakes. The following lesson is meant to work as an introduction, focusing only on prisms and cylinders.
(But don’t worry, there’s another lesson that covers pyramids and cones! 🙂 )
I hope you find this lesson useful, and if so, grab the next surface area lesson, as well my volume exploration!
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