So, today I'm having them produce regents question analysis posters, as a review of both the process of figuring out the answer and as a review of some of the content covered by the most recent test I gave (cells/cell processes). Here's a model of what they will produce on paper ( I did it on powerpoint, which you can download.) I kept the explanations simple and short, so don't get nitpicky about the details.
I say it's only a matter of time before the facts overtake tradition and politics - the sooner the better.
UPDATE
This article from National Geographic, Chimps Belong on Human Branch of Family Tree...(dateline 2003), discusses the issue of reclassification in a little more detail and points out some of the difficulties, among them the confusion that can arise from the domino effect - reclassifying chimpanzees into the genus Homo would necessitate the renaming of several fossil hominids that have been assigned their own genera.
OK. I didn't start this post as a rant, so I'll stop now. We are really starting to get into the meaty part of the curriculum and a lot of students are struggling. There's something more or less intuitive and easy about ecology, where we started the year, but as we get into cell processes it gets abstract very quickly and I don't think a lot of students know quite how to deal with the level of understanding they need for the regents exams. They seem to be groping around for a list of vocabulary words or simple processes or rules they can just memorize. I gave a test on some cell basics, culled from old regents exams. The results weren't impressive. I did allow them to use their books but warned them they probably wouldn't find the books very helpful - since the regents exam requires them to pull together bits & pieces of information from various parts of the book, and apply what they know to novel situations - the answers aren't in the book, they have to be synthesized in the brain. I actually made them work without the books for about 15 minutes, answering questions as best they could, then allowed them to open the books. I may do something similar in the future and find a way to compare their open book answers to their closed book answers to see how much they actually change. Hey, I might even be able to turn that idea into my master's project, with some refinements.
Speaking of master's project, I may have to put that off for another semester. For some reason that class is always in demand and filled to capacity with a waiting list, and I wasn't able to get in. I am on the waiting list, but I won't be that upset if I have to wait till next fall, when I'll have a better grip on my curriculum and materials and will not, I hope, be working 10 hours a day on a regular basis.
My 2nd grade sons (twins, neighborhood public school) just went on a field trip to the Darwin exhibit at the American Museum of Natural History. The whole second grade went and I was sort of expecting to hear some backlash, but so far so good. This was entirely their teachers' idea and had nothing to do with me. They did read a children's book on evolution in class before the trip as preparation - (Our Family Tree: An Evolution Story, by Lisa Westberg Peters). The book was my wife's idea and she loaned them our copy. But I was impressed that the teachers organized and carried it out without much fuss or fanfare. I asked my sons about it afterward and they seemed to actually get the major concept of natural selection, through a computer simulation at the exhibit in which the background color changes over time and the color of a population of prey organisms changes with it. "When the background is green the orange bugs get eaten by the birds and when the background changes to orange the green bugs get eaten." I pressed them a little further and asked what was left when all the green bugs were eaten, and they told me that only the orange bugs were left. Pretty good summary for 2nd graders. I hope my 9th graders get it!
I haven't any particularly new ideas these days and not much in the way of new material - we just did a rinky-dink lab looking at onion and cheek cells under a microscope. It's the kind of lab that I despise but I needed a filler as I don't have an alternative yet. As I've mentioned before I like labs where students are trying to answer a question by measuring or otherwise collecting numerical data and I don't have anything that involves making a wet-mount slide and then looking at the cells for some variation that we can quantify and correlate to another variable. I can think of some possibilities but I haven't had time to sit down and test them out or develop a lab around them.
One idea is to take for example a green onion and look at the different parts of the onion - root tips, bulb, green tips - to see if there is variation in the average size of the cells in these different parts (I'm pretty sure this is based on another lab I've seen somewhere looking at the different stages of mitosis in the different parts - but that requires complicated staining techniques if I remember correctly, or prepared slides). My reasoning is that parts that grow faster (root tips?) will show a smaller average size because there will be more of them at different stages of mitosis - the daughter cells initially being smaller than the parent cells. How would we measure the size? I noticed in our labs that 100x magnification of onion cells gives us a nice, easily countable number of cells within the field of view. A greater number of cells within a given field of view means a smaller average size obviously. If you've done this kind of lab or know of links to a version of it on the web I'd like to know. I could be totally off and there are probably other variables that affect the size of cells in the different parts of the onion that would make a conclusion impossible to draw, so I would really need some time to go through the lab myself to see if it's feasible.
On to human body systems and maintaining homeostasis.
I like to do this lab even though it replicates some of the concepts in the Diffusion Through a Membrane required lab. The eggs are of course a good size to work with and I'm always partial to labs where we can measure the results and graph the data. They also respond pretty consistently and dramatically to the different soultions, making them virtually foolproof if the kids measure correctly (and the eggs don't break - always plan extras). The occasional broken egg adds to the "ick" factor. The basic strategy is this:
Students weigh the eggs before soaking in vinegar. This is the baseline mass that we use for comparison after it soaks in the other liquids, so we are investigating how the egg deviates from that original mass (we ignore the mass of the dissolved shell since it is pretty trivial compared to the overall mass of the egg and the changes we get from osmosis.) We can estimate the original water content (%) in the egg by interpolating from the graph the point at which the change in mass would have been zero - the point where the line they graphed intersects the y x axis. The point where the line intersects the y x*axis represents the point at which the concentration of water inside the cell would be equal to the concentration of water outside the cell. Needless to say the kids get a little confused with the terminology and using a graph in this way. There are a couple of tricky mathematical components to the lab, but all age/grade appropriate - it's just the kids are used to doing math in math class and apparently not comfortable applying the skills to science class. Aside from the graphing, a few kids were uncomfortable subtracting a large initial mass from a smaller final mass (final mass - initial mass) to get a negative change. We also did not simply use the change in mass, since the eggs were all somewhat different sizes in the beginning, so we calculated the % change to control for that variable (thanks to Mathew Davies, my G-K12 fellow last year, who helped me revise the lab).
You need at least 4 days for this lab,longer if you let students soak all the eggs in the various solutions. It is possible to check the eggs at the beginning of the period and have some time left to do other things afterward. You may need to refresh the vinegar after the first day. The eggs don't seem to suffer from leaving over the weekend if you have to start in the middle/end of the week. Have lots of paper towels. I've estimated the water content of corn syrup solutions, but the numbers may be off - something about the nutrition label doesn't make sense, and I got conflicting numbers from the USDA as to the sugar/water content of corn syrup, so check those numbers for yourself if you're concerned about the accuarcy of the details. It's bothersome to me but I can live with the rough estimates.
*I meant the y=0 point, which is actually the x axis. Sorry 'bout that...
