I was poking through Dan Meyer’s blog, and clicked on a few links, and a few more. Like the good nerd-surfer I am, I read (and really liked) this idea from Emergent Math about letting kids get it wrong.
And I appreciate it on a few levels. The first being that kids should get wrong answers sometimes and then change their answers and it’s not only okay, but acceptable to revise things. Math (and most everything else, besides perhaps brain surgery and pen-and-ink drawings) can be played with and fixed and re-examined.
Science teachers are supposed to teach the scientific method. As part of tradition, students make hypotheses, test them, and evaluate the results. My teachers always told me that hypotheses can be correct or incorrect (and sometimes both), but the important part is the evaluation at the end of the report: if you don’t know why your experiment did or didn’t work, it doesn’t matter if you guessed correctly as to whether it would succeed or not.
A few years ago, my compatriot chemistry teacher came up with a lab for freezing point depression involving antifreeze. We ran some quick-and-rough large-scale tests to see if more antifreeze meant a more significant freezing point depression: totally worked! I made up the lab sheet, shrinking the amounts of antifreeze to 1/10th of the original (who wants to deal with large amounts antifreeze, which is hazardous waste?) We’d get some good graphing experience and some class data outta this plan!
The “micro”-scale version did not work. Not only did it not work, the class data gave absolutely zero correlation, and even across classes the results were chaotic and inconsistent. My students were ecstatic: “Guess we don’t have to write those lab reports, right?!” “Oh, yes you do!”
The truth is, I still have no idea why the lab didn’t work, and I haven’t tried to troubleshoot it. It probably had something to do with errors in measuring ice cubes, and/or antifreeze settling between classes. But I made them write reports so that my students would be familiar with having to give absolutely blind guess rationales for their prospective college labs. It also gave them experience with a failed lab. And for them to know that it’s okay for a lab to go completely sideways.
Recently, I’ve been thinking about doing the antifreeze lab again in its failure-guaranteed-state, specifically so that kids are sorta okay (or at least have experienced) a failed lab. At the high school level, students know that labs are supposed to work correctly (that is, with one expected successful outcome), and I think they need to know that stuff won’t always happen the way they expect. And, this “failure” isn’t at their hands, it’s on their teacher’s, which is probably a little gentler for some sensitive kids. But the big thing is, I want to know that they can actually think about the results and pose some possibilities for my errors.