The Great Clade Race

Last year I went to an AP Biology workshop and the presenter shared several resources with us.  One of the resources was The Great Clade Race by David W. Goldsmith. This activity first appeared in The American Biology Teacher, 65(9):679-682. 2003. Here is one link to that article. There are several other resources associated with the Great Clade Race here. Our presenter also shared a set of student questions for the students to use as they walked through the activity.  I reworked that sheet to better flow with my class.  Here is my adapted version of the student sheets.

Each student lab group receives a huge piece of paper, a set of markers, and a set of racer cards that have been stamped along the pathway they take in the race.  Students use the cards to determine what path each racer took to get to the finish line. I encourage each group to plan their race course out on scrap paper first, and then move on to the big paper when they're happy with their map.  Initially, students tell me this is impossible, but after some struggle, they all figure it out.  All the lab groups draw the race out on their huge sheets of paper and we compare them.  At first they exclaim that theirs is different from another, but then they realize the paths are just rotated around a branch point. This leads into the understanding that cladograms can pivot at branch points and still be the same cladogram.

Once they're feeling fairly confident in their cladogram skills, we add another racer--who of course doesn't easily fit within the original paths of the race.  Eventually, they figure out that they have to draw in a checkpoint a second time to get him out of the race--an analogous trait!

Then we're ready to move onto classifying organisms, and so they move onto their clade critters.  In this part they also make a table comparing the characteristics and use it to help them make their new cladograms.  I love how this lab pulls in so many concepts in a step-wise manner.