Cellular Respiration-- not one of the most interesting things we get to teach as biology teachers. I mean honestly, raise your hand if you actually care about the Krebs Cycle? I sure don't. And I've never totally understood why or how it's important for the state to test students on whether more ATP is produced in Glycolysis or Oxidative Phosphorylation. But I digress...
We held our board meetings on yesterday's activities. Here's how I set it up:
Yesterday, I had written a generic definition of "cellular respiration" on the board that they copied down between activities. I didn't talk about it at all, I just told them that they were modeling "cellular respiration" with the ball and stick models.
Today, I asked them to refer back to that definition and create a white board with a verbal, mathematical, and diagram explanation of that definition of cellular respiration using evidence from the two lab activities. They were confused and stumped, but surprisingly game and receptive to the challenge.
Prior to WBing, we had recapped about the "ingredients" in each of the balloons, and even hypothesized a little about each of their role in inflation of the balloon. They had some really interesting theories they were all sure of-- the warm water caused the molecules in the balloon to move faster, causing expansion of the balloon. The warm water dissolved the sugar faster so it could "react" with the yeast. The yeast was a catalyst. The yeast produced oxygen. I just kept telling everyone those were interesting theories.
Most groups used the chemical equation for mathematical (I kinda tipped them off on that), and diagrams of the balloons or models were easy enough-- but they were stumped on the verbal.
In each class, I spend a lot of time with about 50% of the groups firing questions at them, and basically ignored the other groups. I tried to focus on the "weaker" and more uncertain groups. They all had the same questions: "We don't know what you want us to do. These labs had nothing to do with each other."
In my rapid firing, we focused on the glucose and the chemical equation. Glucose was one of the reactants in the model of cellular respiration. Was glucose involved in the balloon lab at all? (Yes, it could be derived from the sugar) Was anything else in the chemical equation also found in the balloons? Where did the oxygen come from? What evidence did you have CO2 may have been produced? Does it seem plausible that this reaction could have happened in the balloon? So if I leave sugar sitting on the counter, it will turn in to CO2 and water, right? (Umm... no...) Then why did the balloon inflate? What else was in the balloon? Re-read that definition-- why did we add the yeast? What did we discuss about yeast earlier?
And then about that time, each group had the most rewarding OH MY GOD I GET IT light bulb moments. :) :) :) :)
My only regret is that these groups were SO excited they "got it" and while many of their peers still didn't... and they WANTED to blurt it out in the board meetings. The groups I spent time with were waving their hands in the air the entire board meeting, wanting to talk... and I reeeeeally wanted to let them show off their new found knowledge. But... I also wanted everyone else to have that same epiphany.
We then did a terribly boring textbook "active reading" session about ATP. Great way to cap that good discussion, huh? But there was a reason. On Monday, we had a district teacher inservice with a speaker who I will not name. He was not one of the better educational speakers I have ever heard. While he made some good points, overall I thought he was extremely antiquated and out of touch with today's students and schools. His big emphasis was on more reading and writing-- less doing, more reading, writing, and note-taking. Kids today aren't college prepared because they can't read textbooks and they can't write papers (I do agree with that part). One of his criticisms of science teachers was that we "do" too much and pride ourselves on not even using a textbook (um, guilty). I disagree with him that you should only read and write about science, but I do think I am doing my students a disservice if they never have to trudge through a science textbook at least a few times. While we do read in class, our reading is usually article-based. The speaker gave me a good reminder to step it up with the textbooks. Reading about ATP was a perfect opportunity-- I can think of no topic more dull to practice reading dull stuff.
Each student received a photocopy of the 4 pages out of the text on ATP and highlighters. We read the first few paragraphs together and discussed how to identify the important points... then I set them free with a guiding question (what provides energy for the cell) and told them to keep highlighting what seemed important. Afterwards, they were to write a paragraph reflection of the reading that answered the guiding question. We discussed our paragraphs afterwards, which was extremely insightful. While many students did fine and wrote great summaries, here is a direct quote from a bright honors student with a 98 class average: "I didn't understand a single thing I read." Hmmm. While I don't think we will be reading the textbook every day, I definitely do think I need to throw it in more frequently.
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