First: Intro with fluorescent minerals. I asked them where they'd heard the term fluorescent before, and if they'd heard the term UV anywhere. They all knew lights and sunblock. I talked to them briefly about sunglasses having a UV coating as well. Duke had done a good intro to light and types of energy including different waves, so the students could also name different wavelengths of light. They all oohed and ahhed at the minerals, particularly the one that is white in regular light but fluoresces yellow in UV. I wanted something a little less abstract for them, since most haven't worked with rocks. So I showed them tonic water, which they'd seen in the grocery store. It glows a beautiful blue under UV light. The quinine in the tonic water is fluorescent. So that got them hooked on wanting to know more.
Second: Went over the Bohr model again (or in the case of second and third period, Duke went over this very quickly at the beginning, which I think helped a lot). Wanted to really emphasize that this is not an electron flying off, but moving between two orbitals. This is the key idea in chemistry we want to get across, so I wanted them to remember this in particular. Hopefully having a fun reason to remember will help it stick.
Third: We introduced the idea of a deep sea core. I passed around the core we took so the students could see it and they could look at the mud and know that it didn't really look different from top to bottom. They all got kind of weirded out when I told them that the stuff in this mud is stuff that is in the water, and that they've swallowed most of it. At this point I introduced the idea of an XRF. They'd heard of fluorescence now, so they seemed to get the idea that if we are shooting x-rays, they behave the same way as other fluorescence. So I told them to show something to them, we always try to find something they can actually see. They would be using a model to learn about a system. So I had a bracelet with the UV beads on and I asked the students what color the beads were. They all said white or clearish. I walked outside with the bracelet on and asked them what color the beads had turned. They said all different colors and were totally hooked. I told them they would all get some, and they were suddenly very excited. So I talked about using them as a core, and how the machine would scan down the core, and look at x-ray fluorescence. They would scan down their cores and look at the number of counts in their core. So we sent them off, doing one question at a time.
The first problem we ran into was that students like to jump ahead to answer questions. So it was a little bit of a struggle to get students to NOT answer questions ahead of time. I would ask them if they knew how to answer it, and they would say no. I'd then tell them it was because we hadn't gotten to that yet, and then they'd just have to be patient.
The students did their counts and took their cores outside to look at them and the sun made the colors really bright and easy to see. Unfortunately it was very hot outside, so the students didn't really want to sit in the sun, and I didn't really want to make them sit in the sun. They were all amazed at how bright they got. So I took that opportunity to talk to them about UV from the sun and the importance of wearing sunblock.
When we came back together inside to walk them through the graphing part of the exercise. So we did a little demo of how to do the graph. Duke did it first period so I could see how he wanted to introduce a graph, and I did it for second and third period. This was a great way to introduce me to how to do this without screwing over first period with a bad explanation. I always explain things a little bit differently from Duke, but it was nice to see the order he did things in and the level of explanation he felt necessary. I have a tendency not to explain quite enough, and it helps me to work with him so I explain more step-by-step.
So we finished up the graph, and gave them some actual elements, then changed top to bottom of the core to time (top = now, bottom = 100 years ago). This way they could say their element changed over time in a certain way. One of the things they struggle with is how to describe something in a way that other people understand it without seeing it. So I told them to imagine they were really really nerdy, and super excited about this graph. If they wanted to explain what the graph looked like to their super nerdy friend on the phone, how would they explain it? That seemed to give them the idea of explaining things more fully than "it went down."
For the next part, we returned to the real core and showed them some actual data. This was the part that surprised me about the students. They were really able to interpret the data well. We talked a little about what the scatter in the data meant. I asked them what they had heard of lead being used it. They were surprising with what they knew. Some examples are: paint, pipes, Mexican candy (the only one that all the classes got!), stuff you put on you during an x-ray (which most of the students had gotten before), toys made in China (which we were specific was not in ALL toys from China). So I asked who had been to a gas station. They all raised their hands. What does it say on the pump? Unleaded. They all had no idea lead used to be added to gasoline. So we got a little bit into additives and why gasoline had lead added in the first place (and what the super, premium, and that sort of thing means). Some of them had been to Mexico and seen that the gas there has lead in it sometimes. So we talked a little bit about their experience with lead. Then we talked about what lead in the environment does, and why it's bad for things.
Finally, we brought everything back to the differences between our model and our actual data. So we compared what we can get from the UV beads to what we can get from the XRF. They always have a little bit of hard time comparing models to real things, so we start off with what they have in common, and go with the differences second. They did pretty good with this, with slightly different responses in each class, and a little filling in by me at the end.
All in all, this went really really well. Difficulties: that students work at very different rates. In the future, it might be good to know the students better and know which ones work faster and make sure they get the two-part cores, so they have more going on than the students that are a little slower. I'm getting to know them better, but I would like to have had a better idea ahead of time. Positives: the students were really excited to learn more, were surprising with what they knew, and were talkative and enthusiastic. They are getting to be more willing to admit they don't know things. That's an important thing for me. I want them to say when they don't know something and not be scared to talk to me about their questions. So we're starting to get to that point.
Anyways, that was the first big lesson. On to lesson number two!
4 comments:
I am glad to read that all went so well. Will you have an assessment to see what the students got from the activity? If so, when and what will it contain? Let's set up a time to discuss this and more details about this lesson and the next one you are working on.
By the way - Socrates Fellows - in this case, is Mark. :-)
Was this the second time you implemented the activity?
Mark, this was the second time we did the activity, yes. We piloted it with a club here (the Preserve Our Planet - POP - club). We did an assessment a week later to see if the students retained what they were learning. And we'll see on the test that Duke is about to give.
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