Monday, December 08, 2003

Chemistry

Test tubes are amazing motivational tools. We did a simple lab activity today to compare physical and chemical changes. The kids had a test tube with food coloring and water, and then added a few drops of bleach. The color fades in about a minute, from dark green to blue, to greenish yellow, to yellow. I also lit a candle and had them observe the difference between the wax changing from a solid to a liquid, and the wick burning and releasing heat, gases, and smoke. Finally, we did the classic baking soda & vinegar experiment, to show that bubbles are a sign of a gas being released. They were very excited by the whole thing, particularly the change in color when they added bleach to their test tubes.

I, on the other hand, was having one of those discombobulated Mondays when, even though you've planned the lesson thoroughly, you just don't feel ready to teach it. Plus, we don't have goggles or aprons, so using bleach made me very, very nervous. Goggles were on the list of science supplies last year, but got cut when I had to trim the list to fit our budget. That was before I'd taught Physical Science! The labs I've done in Earth Science, and most of the labs in Life Science, are not particularly dangerous. We will definitely order goggles for next year, and I think I will even price them now to see if I can get some for this year. Anyway, I demanded full attention, gave out the bleach for only a very short period of time, warned the kids about the dangers of spilling it on their skin or clothing, and designated one person per group to do the actual experiment. No disasters! Phew!

Anyway, planning this week's lessons helped me make my peace with teaching Physical Science. There are lots of great lesson plans on the web, and I can imagine some of them being both fun and informative. For example, I am really looking forward to having the kids experiment with ways to make a solute dissolve faster, or a reaction take place faster. It occurred to me that it's not the end of the world if I don't organize the lessons perfectly; the kids can still get a lot out of them. I need to step back, take a deep breath, accept the fact that I am teaching this for the first time, and look at the positives: The kids are excited about chemistry experiments and will learn so much. Heck, even though I am slightly disappointed by my unit on atomic theory, the kids know much, much more about atoms and compounds than they did a month ago. At least 75% can predict correctly what ion will form from a given element. Virtually all could describe the atom pretty much accurately. They all know what the atomic number is. At least 75% understand ions and isotopes much better than I did at their age! Most can predict which ions will bond to form a compound, and most know how to name the compound, too. They know some of the patterns that underlie the organization of the Periodic Table. Next time, I will order the right materials to do some demonstrations of how elements in one group share properties, but my kids know a bit about that even without demos. They know what the noble gases are, and why they don't react easily. I'm not doing such a bad job, after all, and if I loosen up, make use of internet resources, and get some kitchen chem books from the library, January will rock'n'roll!

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