Current CAT by James M. Thorson

BIOLOGY 121---General College Biology
Evolution by Natural Selection

Evolution by natural selection is the central theme in the biological sciences. It is the process used to explain three-wide scale patterns in the natural world. These patterns are diversity, the procession of life, and the fit of form and function. Diversity is the notion that there are many different species or forms of life on this planet. The procession of life is a pattern of gradual changes in body form from organism to organism when they are arranged in a simple to complex fashion. The fit of form and function is the observation that most organisms function very well in their environment. These concepts are almost ethereal to the students. Instead of boring the students with lofty talk about subjects which they may feel have no effect on their lives, I have them answer a background knowledge probe on a related but familiar topic, domestic dogs.

The CAT--Background Knowledge Probe

1. How many different types of dogs can you think of?
2. Think about the different uses humans have for dogs. Do you think their body features match with their use?
3. Imagine the diversity that domestic dogs have for certain traits. Do you think you could see a procession of gradual changes if you were to organize these traits ranging from one extreme to the other?
4. Imagine releasing 50 individuals of each breed of domestic dog on the Serengetti plains of Africa. Do you think that all the breeds would survive for a year? Which ones would be more likely to survive? Why would they be more likely to survive than other dogs?

This CAT is administered in a handout form. The students are allowed to work in groups while the teacher is out of the room. It usually takes the students about 15 minutes to complete the form. The teacher returns to the room and creates a dialogue with the students about the CAT, noting the analogous situations between diversity and question 1, fit of form and function and question 2, the procession of life and question 3, and natural selection and question 4.

I use this CAT as a teaching tool to help students make a connection between some difficult ideas and objects of familiarity. I enjoy administering this CAT for several reasons. First, it allows students to take some difficult information and relate it to something with which they interact everyday. Plus, all of this is done on their own without the guidance of a teacher. Second, it allows the students to interact with and get to know each other within the first week of classes. Third, the students usually show great enthusiasm because most people have emotional feelings towards dogs, whether positive or negative. And last, the students get a better idea of the three patterns when they do this CAT in my classes compared to when they do not.

Oakton Community College