Just finished the first full period of having my students find surface area of six figures by way of spreadsheets. I learned quite a bit in just one period.
First, as with most of the technology that I bring into the classroom, all the skills my students are learning today can be learned through less invasive means. As I said yesterday, anybody can the find surface area of a figure with a pencil, paper, and calculator. The great thing about the spreadsheet though is that it also acts as an organizer. Students are able to see how the figure (in our case, a prism or cube) is divided into six sides, each having an area. Also, by putting the areas into the cells, their work is not a jumbled mess on a piece of paper. Spreadsheets are also a tool that students need to learn to use to function in the some of the professions they may work in some day. When finding surface area, they master a simple function, the =sum(A4..G4) function. Obviously, you must master the basic before moving on to the more complex functions.
Second, I've learned that the spreadsheet must be one of several tools used to teach surface area. Students MUST have experience with actual three-dimensional objects (have them cut out a 2-D net and tape it together) if they are to learn this concept at all. When shapes are on paper, it is difficult for them to perceive that the shape has a length, width, and a height and even more difficult to figure out what they measure of each is. But when they are holding a 3-D shape, they can turn it in their hands and make the connection between what they are holding and what they see on the paper.