Science is a messy business

A fellow on a biology listserv just blasted cooperative learning and declared, without hesitation, that kids learn best when a teacher stands in front of the room and explains things to them. I hope we one day get past this "one true way to teach" false choice that so many educators are hung up on.

I wonder what his labs are like? I ask, because I have done a series of lab activities lately that were quite messy. Their original purpose was content based - I had a specific content objective that the lab was supposed to demonstrate. In each case, however, I have wound up teaching more about the scientific process than the content, because if I am honest with my students (which I ALWAYS am :>) and help them analyse the results and draw valid conclusions, then all the labs have been inconclusive - they do not conclusively demonstrate the content objective I started with.

Now, I think this is OK, or even pretty cool really. Students learn how difficult it is to control all the many variables that might influence the outcome of an investigation. They learn about the limitations of our measuring tools, about the importance of following a procedure precisely and consistently, the importance of repeated trials or large samples, or carefully recording results and calculating averages, e.g. They even get ideas for exit projects - either re-do one of the experiments and try to clean up some of the mess, or they think of other possible questions to investigate.

A concrete example. I found this series of activities on enzyme action. I am only using the one activity (Mello Jello) to test the effect of different detergents on dissolving the proteins in Jello - some of the detergents have enzymes, some don't:

The jello is prepared and poured into petri dishes, after adjusting the pH with sodium carbonate. Students use a straw to poke wells into the jello, then place a few drops of detergent solution into each of the wells. Tomorrow they will measure the change in the diameter of the wells after extracting the liquified jello with a pipette, presumably the ones with greater enzyme action will dissolve more of the gelatin. I've left out a lot of details, but it's a pretty nice set up, if it works. Of course the set up isn't that easy for 8th grade students. Some of them still have motor skill issues.

I didn't make it any easier for them. I made the gelatin a little too soft, so extracting the plug from the wells was a little difficult. Students had difficulty placing the drops in the wells with the detergent, spilling drops all over the place, probably contaminating some of the wells.

At the end of the period a student asked if she might be able to actually test detergents on clothing as an exit project. She made that connection herself, I didn't suggest it. I think it's a great idea if she pays close attention to the role of enzymes in the process and investigates the variables that affect the enzyme action, the organic molecules that the enzymes work best on, etc. I have seen this activity done poorly, where the only point was to do a product test and little or no science content was developed from it. But investigating enzyme specificity, pH, temperature, etc. seems like a valuable enterprise to me.

I have no idea what results we will get tomorrow. If the results are inconclusive, that's OK. Students will have learned some lessons about the scientific process and they are at least thinking about enzymes, meaning that they might actually be curious enough to pay attention when I have to "explain" it to them.

(Follow up post)