Students seem to think that when you double some of the numbers in a math problem all of the results will double as well. This lesson works from a geometric viewpoint in which students will create and measure rectangles, find the area, double the measurements, and see if the area doubled as well. They will record their results in an Excel spreadsheet. Using this they will also have the opportunity to learn how to create and use formulas in an Excel spreadsheet

This post was edited by Donna Schleicher on Apr, 2008
My students were really excited as we began this lesson. These students are my B-level groups and really enjoy hands-on learning. Since the students would double their measurements in the second rectangle they just assumed that the area would double as well. They made their predictions and then continued creating their larger rectangles and inputting their information into the spreadsheets. As they reviewed their results they were stunned that the information was not what they had expected. Some students took out calculators as they thought the EXCEL program had made a mistake. It was really comical watching them respond to their results and to each others. As a final challenge I asked them to see if they could come to a conclusions as to what really does happen when you double the measurements. A few kids rose to the challenge and were able to tell me that the area quadruples, not doubles. Some even figured out that this is because of the squaring when finding area.