Chapter 3 of Inquiry in Action
We started class by taking a look at the polarity of water. I had them tell me the chemical formula (H2O) so we could continue to review the names of atoms. I drew a picture of the molecule on the board, then had everyone gather in a tight group in the middle of the room (a couple of kids weren't comfortable with being in a big group like this, so they simply watched). I explained that everyone's right hand was positive and everyone's left hand was negative; all of our right hands wanted to touch everyone else's left hands, and vice versa. That was my simple explanation of surface tension -- the water all wants to stay together that way (homeschool kids often don't get a chance to do group things like this, having to rely on imagination). Now, if we all moved over to the wall and decided we all wanted our hands to touch the wall as much as we wanted them to touch each other, that would be like water soaking into paper. And if someone gave us a bunch of red and blue balls, and we all wanted a red ball in our left hand and a blue ball in our right hand, that would be like dissolving NaCl in water (plus, bonus, we would be so involved with the red and blue balls that if we were next to the wall we wouldn't be quite so interested in touching it with our hands).
Then we started the Look-Alike Liquids activities. We divided the class into 3 groups -- 4 students, 4 students, and 5 students (1 girl was home sick). I had an extra adult helper, so that was really handy. We passed out the labelled eyedroppers. Each group needed a total of 5 eyedroppers for the day's experiments. WHERE TO FIND THAT MANY EYEDROPPERS: Our co-op had 10 eyedroppers already. Discount School Supply has them fairly cheap online, although you'll have to pay shipping. Dick Blick also has a decent price, but again, you'll have to pay shipping (annoyingly enough, the local brick-and-mortar store doesn't stock them). You can also get pipettes from Amazon.com and use Prime shipping, if you have that (I haven't tried these pipettes yet, but I have a dozen for next week). Also, Walmart has 2-packs for $1.37 in the pharmacy department, although the Walmart I went to only had one package.
Also, the Inquiry in Action suggested using little disposable condiment containers to put the liquids in. I found Diamond brand "Multi-purpose mini cups", 50 cups plus lids, in the plastic cup aisle of Walmart near the Dixie cups. These are essentially the same thing; this saved me having to go to some sort of fast food place and taking a boatload of their condiment containers. It occurred to me that little foil petit four papers (like you'd use for mini-cupcakes or somesuch) might work.
The Inquiry in Action directions suggested taping these to the table to prevent spills. I didn't do this. Wow, TAKE TOWELS ALONG! Really, we had spills all over the place! And it wasn't just a matter of knocking over the containers -- some of the kids really weren't that great with how to drop liquid a single drop at a time out of an eyedropper, and therefore were squirting an entire dropper full onto the paper and all over the table. I had wondered about that, especially with some of the younger boys -- it's something that's worked on in the Montessori classroom at a much younger age, but I had a suspicion that some of these kids had never had the experience. Even the ones with coordination seemed fairly clueless about how much liquid they needed to suck up in the dropper ("I need more alcohol!", "No you don't -- you only need 1 drop, and you have about 1/4 teaspoon in that cup, which is gobs-a-plenty"). There was also a tendency to set the eyedropper in the cup, leaning it against the side, often flipping the entire thing over.
So, anyway, I'd been mentally (and physically) prepared for the chaos of having liquids go all over. And I was therefor able to stay pretty calm when the chaos developed. Also, let me say it again -- having 3 adults to help with 3 groups of students was SO GOOD. High school age students would also make great helpers.
A bonus was that by having more adults working with the kids we were able to direct the kids to write more on their lab sheets, and have more small group discussion with them.
I had only prepared to do 2 of the activities within the hour-long class -- Look-alike Liquids, and Developing Tests. By the time we cleaned up everything we had about 10 minutes left of class, so we headed outside to take advantage of the gorgeous weather (60F in January!). Next week we'll try combining liquids during the 3rd and 4th activities.