Tuesday, April 19, 2005

This week in Ms. Frizzle's class,

we are taking tests.

Monday, I did a presentation on gymnosperms. The root of this word is interesting; it means "naked seed." Gymnosperms are basically plants that produce seeds but not flowers or fruit. The types are conifers, ginkgo, cycads, and a very odd collection of plants called gnetophytes. The only one you're likely to have heard of is the plant that produces ephedra.

Teaching the kids the lifecycles of angiosperms (flowering plants) and gymnosperms has proved a bit challenging. The textbook introduced plants by saying that all plants have two generations in their lifecycles, the sporophyte and gametophyte generations. In ferns and mosses, these two generations are fairly distinct and make sense when explained clearly. In seed plants, however, the gametophyte generation is tiny (just a few cells) and fully contained within the sporophyte plant. The textbook - and most teachers - kind of gloss over it and just say that the anther produces pollen which is sperm and the ovary produces ovules which are eggs. But the truth, as best as I can summarize it, is that the anther produces microspores which grow into pollen grains which are the gametophyte plants which then produce sperm, and the ovary produces a megaspore which is the gametophyte plant which then produces an ovule. That's still a bit rough as I must admit the concept that there's another whole generation of "plants" in the middle of the lifecycle is a bit hard to get my head around. The breakthrough came when I realized that the crucial detail that makes the gametophyte plants separate plants and not just small parts of the sporophyte plants is that they have different DNA due to meiosis.

So, does a middle school student need to know this? No. But if I tell them that all plants have these two generations, and then gloss over the gametophyte generation for two kinds of plants, someone is going to ask a question. And then I will have to go into it. And I also think, from my own experience, that it was much harder to learn about the two generations later, after being taught a simplified but not really correct version the first few times we covered these topics. In the end, I was honest with the kids and explained my reasoning in teaching them the more complicated version of things. And for their test tomorrow, there are a few multiple choice questions that deal with the basics of these lifecycles, and then I ask them to explain ONE of the four types of plants in detail. So they can go with their strengths and wait for reinforcement in high school if they don't quite get all the finer points of microspores and megaspores. I think it's good middle ground.

Today was a review day. I gave out study sheets and gave them an hour to review their notes, the textbook, handouts, etc. and to ask me and their classmates questions. I was pleased to see that most of them used the time well. They definitely have a better idea of how to study than they used to.

Tomorrow is the plants test.

Thursday and Friday I am going to give a practice test for the Intermediate Level Science Exam for diagnostic purposes. I think they are in pretty good shape although we have a lot of topics left to cover this year - but the human body should go quickly and be motivating material, and I just have to sneak the basics of genetics in before June 8th to ensure that they can handle simple Punnett squares. We've skipped most of ecology, so that might be a vacation packet since the ideas are simple enough. I will analyze the practice test to see if there are any areas where all students need review or a quick intro to a topic and then decide how I want to handle test prep. I'm crossing my fingers that what they already know will be enough - which is how it should be, in an ideal world - and that I will have to do only minimal review.

And then, vacation. I think about half of vacation will be spent grading all the stuff I am collecting this week!

1 Comments:

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10:26 PM  

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