A lab team called me over as students got to work on their brine shrimp investigation for the day. “We wanted to know if there was a way to filter out our brine shrimp.”
“Can you be more specific?”
“Well, we want them all to be eggs, but this liquid culture is mixed with adults and eggs. So we thought if we had some kind of funnel or filter, we might be able to sort out the adults from the eggs and then just have the eggs.”
“It sounds like a good idea, but I’m not sure we have the materials you would need to make a funnel that precise.”
“Can we try?”
For the 15 minutes or so, I watched with interest as the lab team tried to make a funnel for their brine shrimp culture. First, they tried just making a paper cone with a small opening. This was quickly rejected; it absorbed droplets of water, making it useless. There were a few sheets of transparency lying around the lab area from a previous experiment. The students asked me for a thumbtack because they figured that opening would be large enough for brine shrimp eggs but too small for adult brine shrimp. They punched a hole in the transparency and folded it into a cone shape. At this point, another lab team flagged me down.
“We have a problem,” one of the students announced as I approached.
“What is your problem?”
“We were testing the effect of light on the brine shrimp,” explained the student, gesturing toward the lamp they had focused on one of their small jars of brine shrimp. “But this jar got really hot. So now it’s light and temperature.”
“OK. So what are you going to do about it?”
“We don’t know,” she admitted.
“Well, you have a couple of options, right? What are your options?”
“We could test something besides light.”
“You could. What else could you do if you still wanted to test light?”
“We need a way to keep temperature the same. Light without heat,” added one of her classmates.
“I agree. So what can you do?”
“Wait … Could we use a water bath like a heat sink?”
“Sure. Can you explain to your lab team why that might work?”
“Water has a high specific heat, so it would absorb some of the heat from the lamp but still let the light through.”
“I still think we need a thermometer with the set up, just to monitor,” replied her teammate. I left them to it and went to check on the filter group.
“How did the transparency work out?” I asked, genuinely curious.
“It didn’t.” The student held up the makeshift funnel. “The opening is so small that it doesn’t break the water tension.” She demonstrated for me: When water from a pipette was squirted into the funnel, none dripped through the hole. “We’ve given up on the funnel idea.”
Across the room, two lab teams were consulting each other about how much yeast to add to their brine shrimp jars. “No, 0.2 grams is way too much,” said one student, holding up a jar that was opaque with yeast. “We’re trying again with 0.1 grams.”
“Well, we’re just going to wait to see what happens,” replied a student from the other group. “Let us know if it works.”
And so for about six weeks, my AP Bio students spent 30 minutes a day in the lab working with their brine shrimp experiments. The experience was not one that I had really planned for them. Initially, I wanted them to engage with some quantitative ecological data collection. While reading “The American Biology Teacher,” I encountered a description of an aquatic ecosystem modeling lab that allowed students to count populations of algae and brine shrimp. I worked to set it up in my classroom lab, but I ran into many unexpected obstacles while trying to create protocols for my students. First, the microscopes available to my students were not high quality enough to make the algae counting easy. I printed out millimeter grids on transparency in order to facilitate cell counts. This helped. Culturing the algae also presented me with some difficulty. The only thing that went well, in fact, was the hatching of the brine shrimp. We were already a week past when I had intended to begin their lab work when I finally realized I needed to either abandon the original lab design or abandon the whole ecology data collection experience. I scrapped the original lab design and instead just asked my students to generate some questions about brine shrimp and algae. They were then set loose in the lab to try to answer their selected question.
Throughout the experience, I was not very helpful to them. Most of them learned much more about brine shrimp in a week than I had known about brine shrimp. Some of the problems they ran into I anticipated - like the temperature being a confounding variable when investigating light - but other problems surprised me, like the difficulty of optimizing a yeast solution for our small brine shrimp colonies. They were forced to talk to each other, because they were all dealing with high mortality rates in their colonies. They shared sampling methodology with one another and asked impressively specific methodological questions of one another.
At the end of six weeks, they voted as a class to process the experience in a Socratic seminar. I asked them, bluntly, “Should next year’s AP Bio students do this experiment?”
“I don’t think we got particularly good data, and I don’t think we really answered our experimental question,” said one of my students. “But it taught us to work through our errors and precisely design an experiment.”
“We were doing real science. It was worthwhile,” added another student.
Brittany Franckowiak is a science teacher at Wilde Lake High School in Columbia, MD. She is a University of Pittsburgh alumna, a 2011 Knowles Science Teaching Fellow, and a member of Cohort 2 of the BSCS AP Biology Leadership Academy. Brittany spends her breaks from teaching exploring national parks, experimenting in her kitchen, running slowly, and visiting her family in Michigan.