This student sheet was designed to accompany and interactive timeline available through www.pbs.org. The link to the timeline is on the activity sheet. I typically do this in conjunction with the activity ""Who Was Darwin?", which is also available on the PBS site. I generally do the "Who Was Darwin?" activity first. I then discuss the fact that Darwin was not the only, or the first, person to develop an evolutionary theory. I give them a little background on some major players (such as Lamarck) and then introduce the activity. It takes the rest of the intro class period and two more forty minute periods. Computer access is needed.