What would you like to do first? You could pour plates, use a pipetteman, measure pH, and use an autoclave. Or you could test an idea of your own with fresh samples, using plates poured by someone else. This question is fundamental to how we introduce students to research. What should come first, techniques or questions?
I, for one, prefer to learn how to use tools after I need to use them. If I want to chop up some DNA for an experiment, and get it to a certain size, I’ll learn all about which restriction enzymes work well together, and what size pieces they make. I wouldn’t want to just memorize all that stuff about restriction enzymes without needing them. If I use them enough, though, I would naturally learn them.
But when undergraduates come into our laboratory for independent study, or as work-study students, there is a certain efficiency to teaching them a couple of months of tools. At the same time we have our Wednesday evening talks, so they can see what the point is. So Lucy, Alicia, Eamon, Matt, Thomas, and Amy have spent the last 6 or so weeks learning tools. Now they are doing a simple experiment of our design on their own. Boahemaa has done a great job training them, though it has taken a great deal of her time. After this experiment, they will be ready to do much more independent work under the guidance of our grad students and postdocs.
Can we do an ideas-first approach also, even though our work requires a lot of experience to keep the little amoebae and their bacteria food happy? Even though counting them is part of every experiment, and that is not trivial to learn? We are giving it a try with the three new students we just got as part of the Eureka program. They only come in one afternoon a week, so tools-teaching would be slow. We gave Juan, Dami, and Kai reading in a general article on social amoebae, published in 2009 in the Animal Behavior Encyclopedia. I hope your library has it, because it is pricy. Or you can email me for a PDF. Then we gave them a little quiz at our first meeting. This quiz follows from the documented evidence that testing enhances knowledge retention. It was discovered here at Wash U by Roddy Roediger and collaborators. They have a whole program on this fascinating approach.
Juan, Dami, and Kai bent over their papers, writing answers to the first-day quiz. It was short and open book, but they were mostly not opening their readings. It was a simple quiz, asking what Dictyostelium is, why people study it, what is its life cycle, and then the most important, what interests you the most. We discussed their answers, focusing on the life cycle and on their own interests. I told them they needed to come up with a question that interested them enough for an experiment. It should involve where they expected to find the most Dictyostelium, since we were going to go collecting and culturing.
They should come up with the hypotheses, but I gave them the experimental framework this time. It involves replication more than everything. We should have at least 2 separate sites for every condition. Within each site we would collect at 3 different places. We would be collecting tiny amounts of soil in drinking straws. So they would end up with 12 straws, half from one condition, and half from the other. Within those halves we would be able to detect differences in location due to something other than the experimental variable, we hoped. We then brainstormed over the kinds of things that might cause Dictyostelium abundance to vary. They suggested sunlight, moisture, soil density, level of human disturbance (on a trail or not), salt (near the road), soil depth, plants overhead (height, native species), and whether it was on dung or not. It was a good list.
By the next week they each had to have a hypothesis. Juan expected more Dictyostelium off trails because there would be more moisture. Dami expected more Dictyostelium in gullies, also because of moisture. Kai expected more Dictyostelium where there was more leaf litter to grow the bacteria they eat. Next week we’ll go out and collect soil samples, then plate them out. Should be fun!