Students practice classification using a bag of snack mix. Each group examines and decides how to sort the contents. They can classify the foods based upon physical characteristics such as color or texture, or whether the food is eaten at breakfast or as snacks. Students then draw a taxonomy tree that shows how they organized the snack mix. For example, students may have sorted the food into snacks and breakfast food, and then sorted the snacks into salty or sweet.
Taxonomists -- scientists who classify organisms -- sometimes use a dichotomous key to identify specimens. This is like a flow chart that separates organisms based upon characteristics. Students gather living and nonliving specimens from an outside area. Then they sort the items using a list of physical characteristics provided by the teacher, such as number of legs, odor or whether they are man-made. Using this information, the students create a dichotomous key that other students can test on their own collection of items.
There are seven commonly used levels of classifying animals: kingdom, phylum, class, order, family genus, and species. Every organism that has been classified has names for all of these. In this activity, students become familiar with this system by classifying three familiar organisms from kingdom down to the genus and species. They can use field guides, textbooks and the Internet. For example, humans are classified as: Animalia (kingdom), Chordata (phylum), Mammalia (class), Primates (order), Hominidae (family), Homo (genus), sapiens (species).
Using nested plastic bags and index cards representing organisms, students model cladistics, a type of taxonomy based upon evolutionary relationships. Students write on the outside of the bags the characteristics shared by the organisms. The largest bag shows the traits shared by the greatest number of organisms, and the smallest bag the least common ones. Students place the cards inside the bags for organisms that have the characteristics on the bag, starting with the largest bag, and moving cards among the bags. In the end, the bags represent the hierarchy, or taxonomy, of the organisms.