Sunday, March 27, 2011

Limited Resources: What Now?

I've been quiet here recently, mostly because I've been traveling and haven't wanted to take time out to type up my thoughts. But they've been in my head for a while, and here they are.

Peter asked an interesting question in this post:

"What do you see as an alternative to a teacher who doesn't have he resources to have all the students participate in a lab, but still wants the concept to be taught?"

In my response, I suggested that if a student could successfully design an experiment--even without carrying it out--that should be evidence that the aforementioned student had sufficient comprehension of the ideas he or she was testing. I've actually done this myself--see this post (I know, I know--slideshows=bad. I was just getting tired of doing complex prezis for everything).

All that I really did, though, was design an experiment to test a certain question. (I can't claim that I knew everything, though--I did have information on the reactions between BTB, water, and carbon dioxide.)

Now, let's try this, and see if this can work to show if student has real understanding. Imagine the overall goal of a class period was to extract DNA from an organism--say our student chooses wheat germ. First off, we'd consider what needed to be done to isolate the DNA. We'd have to break down the cell membrane and the nucleus somehow so that the DNA could precipitate. At this point, the student (let's call her Jill) would have to come up with something along the lines of, "Because wheat germ has a phospholipid membrane, hot water and soap can break it down."

Ok. So, now we have a bunch of DNA floating around in water. What next? 

Well, let's ask Jill. "DNA isn't soluble in alcohol. So, if we add alcohol to the raw DNA, it should pull together into a precipitate."

Of course, I recognize that there are major flaws with my presentation here. After all, Jill would have to know that wheat germ has a phospholipid membrane which can be broken down by hot water and soap, and that DNA isn't soluble with alcohol. But that's the problem with examples. In a real classroom, these topics could either be covered ahead of time or Jill could be given this information (like I was on that experiment over photosynthesis). Then, of course, Jill would need to figure out how to apply these facts to obtain her desired result.

And isn't that skill what education should be about? 

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