Many students won’t find either of these animals particularly fun and exciting.  You can however, make things a  little bit more interesting by including a lab component or at least have specimens on hand for students to play with.   When we talk about sponges, I pass around an organic sponge for students to compare to a store-bought (synthetic) sponge.    (You can order the organic sponge from biology supply companies or even pick some up from bath and beauty stores.)    As they play with the two sponges, ask them to make a judgment about which one can absorb more water, ask them to compare they way they look.

I also have several specimen jars that contain jellyfish and the portuguese man of war.  For some reason, the air bubble in that hydrozoan fascinates students.  They always want to know what would happen if they popped it.    Finally, students are allowed to view the hydra under the microscope.  This small organism is visible with the naked eye, but more details can be seen even at low power – like the cnidocytes on the tentacles.   See hydra lab for a printable for students to complete.  I was able to capture a hydra doing a cartwheel on my slide – watch this amazing video!

The first step is to create that “oooh” moment when students are amazed and surprised by something.   This moments are of course, short-lived, but they do help motivate and encourage students.  Do not start your protist lab with something difficult to find – start it with something that’s easily visible.  My favorite is the Euglena.  It is not the largest of the microorganisms, but most sample jars will contain so many of them that they simply can’t be missed even by the most amateur biologists.    I will hold up the jar of euglena, which will usually have a green tinge and ask what they think makes the water green.  Students are then directed to put a drop of the water on a slide (with a cover slip) and look at it under the microscope.  There is your “ooooh” moment.   ( See printable worksheet on algae lab )

Paramecium and Ameba while larger and arguably more interesting than the euglena are the next object of study.  At this point, be sure to tell students that the organisms are a little bit more difficult to find – paramecium because they move so fast and amoeba because they move so slow.  Having preserved slides are a good way to start this exercise so that students at least know what they are looking for.  I also find the microscope camera hooked up to computer’s usb port to be extremely valuable in helping students identify the actual specimen they are looking for.

Tell the students to be patient  (and remind yourself to be patient also) in looking for the organisms.  You could even enlist older students to come into your class to help you circulate around the room and help younger students with the focusing of the microscopes.  My AP biology students actually like coming in to help with the freshman.    Hopefully your patience and their efforts will pay off – I personally think there is nothing more amazing and “ooooh”-worthy than watching an amoeba move.   Below is the amoeba I captured with my microscope video camera while the students were watching.

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.

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.

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