In my nonmajors biology class, our first lab of the semester is about the process and tools of science. Students get to practice with hypothesis-testing, the elements of an experiment, showing data in graphs, and metric units of measure.
The lab has undergone occasional bursts of evolution. Long ago, we had students measure the weights, volumes, and lengths of random objects and weigh piles of butter, sugar, and gelatin equivalent to the fat, sugar, and protein in a Snickers bar. Then, not quite as long ago, we made a big improvement: we adopted a “paper towel absorbency” activity, in which students had to use rulers, balances, and pipettes to determine which of several brands of paper towels was most absorbent (see, for example, this ABLE mini-workshop by Laine and Heath). They had to figure out their own methods, and each group used a different technique, so it was a good exercise for demonstrating multiple ways to approach the same problem.
However, it is probably fair to say that paper towel absorbency is not the #1 issue on the minds of our students. So I was happy to stumble across an article called “Sex and the Scientific Method: Using Condoms to Engage College Students” (Dorothybelle Poli, August 2011, The American Biology Teacher, p. 348). The basic idea of the lab is very simple: Have students ask and answer their own questions about condom strength, size differences, stretch, expiration dates, country of origin, and so forth. It’s reinforcing the same skills as our paper towel activity, but condoms lend themselves to questions that are a LOT more interesting to students.
I am happy to report that the lab went really well. Typical experiments included determining how far a condom could stretch (see photo at right) and counting how many marbles or measuring how much water condoms could hold without breaking. Some groups even tried to correlate a condom’s weight with its stretchiness, but most groups simply predicted that some condoms would be stretchier than others.
One of my main concerns was that some students might be too immature to handle condoms in a lab. For example, we had each group use the Explain Everything iPad app to present experimental methods and results; I secretly feared that at least one group would try to stretch a condom over an iPad, but no one did. Nor did anyone sling condoms full of water across the lab, pour water on an iPad, or make lewd condom-related suggestions.
That is not to say that all was perfect. One problem was that some groups gravitated toward the easiest experiments (i.e., measuring the length to which a condom would stretch); they were done much sooner than groups that chose more time-consuming (and more interesting) experiments. Next time, I think I will require groups to incorporate two or more types of measurements (length, mass, or volume) into their experiments so they have to be more creative and can’t get away with just measuring the stretched length.
A second problem was that most groups did not seek patterns beyond just predicting that brands would not perform equally. For example, I hoped they would survey the types of condoms available and seek patterns — they might have asked whether ultrathin condoms are consistently stretchier than “regular” ones, or whether ribbed condoms are the strongest. Next time, we will provide a worksheet that will help students think through and justify their variables and predictions, and perhaps even have them make a graph of their predicted results.
Finally, we need to tweak the materials we have available for students. The marbles were hugely popular, but we didn’t have enough to go around; you would be surprised at how many marbles a condom can hold! Next time, I will provide something heavier, like metal BB’s or ball bearings, which should cause the condoms to break much sooner than the marbles did.
Overall, however, students and TA’s agreed that the new lab was a huge success. Thank you, Dorothybelle Poli, for giving me the nerve to take a risk and try something new!