How to Explain Taxonomy
Taxonomy is one of those subjects that seems very straightforward. Almost all students start by learning the classification system - Kingdom, Phylum, Class, Order, Family, Genus, Species. And hey, students are great at this, give them a little mnemonic to help them remember it (King Phillip Came Over For Great Soup) and you can have them chanting the system in no time. I remember my first year I was so proud of my students for remembering the system, patted myself on the back and thought what a great job, students know this stuff for sure.
Problem: They can say the words, but they don’t understand what it means. Don’t believe me, try this: after your students can list the words (kingdom, phylum…etc) ask them this simple question. “Which group would have more species, phylum or class?” Chances are, you’ll look out to a bunch of blank faces or a few of them wildly guessing. Pick out the one kid that always has the right answers and ask him to explain his reasoning for guessing the way he did. You might be shocked and dismayed to realize that all your hard work in teaching them Linnaeus’ system seems to have amounted in great memorization skills but very little understanding at all.[ad#Adify Large Square]
So, how do you solve the problem? I find that it’s important to start off on the right foot, explaining why we need a classification system at all. I make an analogy with a grocery store, by asking the students to imagine going into a grocery store to get a list of items: eggs, milk, cereal, grapefruit, and apples. Are there items on the list that you’ll find closer than others? Are all grocery stores laid out in about the same way? This analogy serves as a springboard to explain why it is necessary to group organisms to make it easier to find information about them and to compare groups.
The second activity involves asking the students to make a list of all the flying organisms they can think of. I usually have them work in pairs and give them a time limit to list all the things they can (like a game). Once each group has the list you can even give awards to the groups that came up with the most organisms. Now that the list is complete, ask them to divide their organisms into 2-4 groups. Pick a few to show as examples on the board and point out that not everyone has the same exact groupings. Ask them if there is more than one way you can group the organisms. In this way, you are showing the students that taxonomy is a dynamic discipline, biologists often group and then regroup when new information is found. A hyena was once classified in the same group as dogs (canines), but DNA evidence now suggests it is more closely related to cats (felines).
Finally, to explain the system itself, another analogy is useful. I use a computer (or IPOD) analogy. Ask students why computers have folders. Ask them to describe how they organize their files or mp3′s. The idea is that you’ll show how one folder can have subfolders in the same way that we group organisms into groups (such as Kingdoms) which have subgroups (Phylum). Overall, the main idea here is for students to understand not just the list of groups, but why and how organisms are grouped within the system.
Taxonomy- Interpreting Graphics is a useful worksheet that can help students understand groups and subgroups. More advanced students can try the Taxonomy Project where they must create their own classification system for imaginary organisms. Word of caution though, the project can be very frustrating for teachers and students they do not have a firm grasp of Linneaus’ system. If you are looking for resources about phyla, groups of organisms, and scientific names, the Tree of Life Web Project is an excellent resource.