Candidate's Statement on Teaching - Lee College

Critical thinking exercise #1: Taxonomy
Many students have difficulties with the concept of taxonomy and phylogeny, and how
biologists organize the millions of different species that make up the living world. As a prelude
to this exercise we talk about evolution and how it occurs. Basically, over time different
populations of the same species accumulate characteristics that are different from other
populations of the same species, and ultimately accumulate so many different traits that they
become different species. But because these new species share similar ancestors, they still share
many of the same characteristics (i.e. they may look very much alike). So the challenge for the
taxonomist is to find characteristics that allow them to differentiate between species. In order to
simulate this task, I break up the class into 4-5 teams and give each team an identical bag of
hardware:
Their first task is to look at the hardware and come up with a list of characteristics (traits)
for each individual piece. Students usually start this list with shape, size, and color. Others also
list the presence of threads, the presence of a slot, and maybe the presence of a “barrel” or
“head”. Given these traits, they then need to figure out what is more closely related to what. At
this point, students usually want to “marry” one piece of hardware to another, and have other
pieces give birth to other species. While crossing (hybridization) can in fact occur, these
interactions usually produce infertile offspring. Therefore one of the rules of this exercise is
there is no “marrying”; one species gives rise to one or more new species. When doing this I tell
them they have to be prepared to justify how they create their hardware family tree, there has to
be some rational reason to group species and lineages. Students come up with a range of results,
some more justifiable than others, they can look like this: