10 year old geometry help

[wildmonkeys]

My 10 year old son is having trouble with the concept of surface area. I have shown him the formula, but I can tell that he can't visualize WHY that is the formula. Does anyone know of any good resources/approaches for helping him to visualize and become more confident about determining surface area? Thks!

[Ruthla]

I'd suggest getting physical objects that he can actually see and touch. Covering objects with graph paper might help- he could actually count out the number of squares that cover a cube or rectangular prism (this technique works less well for spheres, the circle parts of cylinders, or triangular prisms, since the boxes will be cut and are harder to count- but it still shows how the edge of the triangle is one side of the rectangle on the sides.)

I demonstrated the surface area of a cylinder (without learning how to spell the word ) to my 13yo with a can of food: I loosened up the label, keeping it attached at one side, and showed her how it rolled around the can to form a circle, then unwrapped it to show her how it was a rectangle, and the side was the length of the circle at the top and bottom.

[Dar]

Yeah, I like Ruthla`s idea. I`ve used cereal boxes... if you cut it open along the edges you can see all of the rectangles.

[wildmonkeys]

Thanks! We are just working on squares and rectangles now so the cereal box idea should do it! (and with my crew we always have a ton of cereal boxes to work with!!!)

[zeldamomma]

You could also let him watch the Khan academy video on area and perimeter-- there's a corrected arithmetic error in it, but he explains the concepts clearly.

http://www.youtube.com/watch?v=kqqmJ...=youtube_gdata