Folding Up!

Deriving Surface Area Formulas in Mrs. Gutierrez’ Math 8 Class...

Students were given a sheet of paper and asked to fold it as many times as wanted in the same direction.  After folding the sheets, they labeled the base and height of each resulting rectangle using variables and then taped the figure closed and stood it up to create a prism.

“When I asked my students to find the lateral surface area of the paper, most students immediately noticed that the area of the sheet of paper was what we were looking for.  BUT what I found interesting was that some students, when I let them struggle, wanted to find the area of each section of their paper and then add them up.  Another group of students found it more efficient to add all of the bases together and then multiply by the height.  This allowed me to have a rich, authentic discussion about using the distributive property and factoring.  Once students realized they were all doing the same thing, they decided that the best method was to all up the bases and multiply by the height which was the same thing as the perimeter of the base times the height (Ph).  Students walked away with a better understanding of the lateral surface area formula for prisms because they came up with it on their own.”

 When have you had those teachable math moments that you couldn't pass up?

(Rosa Gutierrez teaches 8^th Grade Mathematics at YES Prep Southwest in YES Prep Schools.)