Decimals and Transformations

I have been very pleased with the last two discussions that I've led. Last time I came in with a presentation that introduced the concept of tolerance in measurements. We started out by discussing significant figures and why we sometimes write 90.0 instead of 90 when specifying a degree measurement. I explained to them that it is more specific to say 90.0, because that covers a small range from 89.95 to 90.05 whereas saying 90 covers the larger range of 89.5 to 90.5. We all agreed that a lower tolerance (higher accuracy) will result in a higher-quality product, but a higher tolerance will be cheaper. We then discussed the purpose of tolerance and how we can never produce something with 100% accuracy. To end the discussion, I gave some examples of things that might be designed, and we talked about whether we'd want a high or a low tolerance in their designs. While this didn't pertain specifically to the curriculum, I think it added something to their understanding of why we use decimals sometimes. The classes were engaged, and I think they are still interested in the things I have to say.

Since I had some serious problems with the fifth hour class in the past, I started out in that class by reminding them why I'm there. I just wanted them to realize that I'm taking time and making an effort to talk to them about interesting things, and I let them know that I'm open to feedback. That was fairly successful, and they were respectful and mostly attentive for the entire talk.

Today I came in with a talk that supplemented last week's class lesson on rotations and next week's curriculum on transformations. The discussion centered on electricity generation, which is something that I really enjoy talking about. The talk was a little bit longer than I had planned, and a lot more of the focus was on electricity generation and renewable power; although this isn't the main goal of the class, I think it's educational and the students were attentive and interested. So I introduced electricity and talked about the different sources and their pros and cons (fossil fuel causing air pollution, nuclear power creating radioactive waste, and renewable versus nonrenewable sources). We then got into a discussion on wind turbines and how turbines work. I had a 3D CAD drawing of a wind farm, and we discussed how that drawing would be built - the main take-home was that you can save a lot of time by using rotations and translations to create an accurate and robust CAD model. I ended by asking an open-ended question about where else in design we might use transformations, and got some good responses.

Overall, this went much better than I had expected. Because energy is such a hot field right now, the students understood its applicability to their lives, and there were lots of questions in each class. As usual, third hour was the most engaged, and I think that's because they are awake enough at 10:00 to mostly be able to listen to what we talk about. Fifth hour was also more engaged than they have been in the past, which was great.