In a math class at Northbrook Middle School, for example, teacher Julie Johnson has found that technology supports enable students not only to produce higher-quality graphs, but also to understand graphs at a deeper level and to be able to examine the relative strengths and weaknesses of different graphic representations. Students first estimate the length of various parts of their own bodies (e.g., wrist circumference) and then make actual measurements. Both sets of data are entered onto a spreadsheet, from which students can begin to experiment with different ways of representing the data. Because the physical production of the graphs is handled by the computer, students can focus on making the conceptual link between the spreadsheet data and the visual representation. They work collaboratively to determine what information to display and how best to display it. After trying a variety of representations (e.g., pie, line, and bar graphs), they are able to discuss the advantages and disadvantages of each for different types of data sets (e.g., pie graphs can only display one variable).