Conduct your experiments in the lab - click here to see what to do
OR
Search the web for some data that shows a linear relationship. You might look at salaries in professional sports, olympic records, total sales of a product, memberships in an organization, populations (human or animal), braking distances, wind chills, etc. Remember that you need to look at 2 variables (like time vs. dollars) in order to make a graph. Use a search engine such as hot bot, lycos, etc. or try one of these sites:
http://www.informationplease.com
http://www.espn.go.com/editors/atlanta96/almanac/index.html
gopher://jse.stat.ncsu.edu/11/jse/data - look at the document (.doc) for a description of the data first.
Once you find your data, print it and record the source; next make your graph and equation. Be sure to label your axes with the scale used and what variables they represent.