When you identify and control variables that affect the outcome of an experiment, you state which factors could affect the outcome of the experiment and you make sure that only one of those variables is changed in any given test.
http://www.youtube.com/watch?v=pyfM_fKSICE&feature=related
Suppose you are trying to design an energy efficient house. You want to know which wall and ceiling insulating materials work best so the house can be cooled and heated as inexpensively as possible. You also want lots of windows in the house so you can take advantage of natural light during the day. Windows however, are where a house loses most of its warmed or cooled interior air. So you want windows that are good insulators but still allow light to pass through freely. You have a choice of three wall and ceiling insulating materials, and you have a choice of two window materials. You decide to build several small buildings the size and shape of doghouses for your test.
1. What are you testing?
2. What are some variables in your test?
3. Which of the variables will you control?
4. Will using doghouse size models give you accurate results? Explain.
