The theme for today? CHEMISTRY! The morning’s lecture covered the chemistry of water, as well as organic molecules, followed by the WEIRD WATER lab, which was super duper fun! In the afternoon, we had a detergent boat regatta, and then went on a whirlwind “Tour of the Cell,” before which I activate a shrink ray in the classroom. (I have to shrink the entire class at the start of the tour, so we’re small enough to take a submarine ride through a plant cell).
I couldn’t remember quite what we did during last year’s Weird Water lab (Derek and I co-taught the course last summer, and he came up with that activity), so I put together a bunch of new stuff. It was a rotation lab with six stations:
- The Structure of Water, where they built water molecules out of gum drops and toothpicks. I especially loved listening to them work out how the molecules should fit together. I had each group make two or three water molecules, and then link them up with those made by the previous groups.
2. Solutions and Suspensions, where they mixed different substances with water to see what would happen. I had a selection of common food items: salt, sugar, oil, bouillon, flour, and cinnamon. (I know some of the containers say “sauerkraut,” but I had just used the empty containers). Some of these will dissolve, and go into solution; others remained suspended. The one that surprised me was the bouillon – I thought it would dissolve, but it didn’t – I think if we’d added some heat, though, it would have.
3. Adhesion and Cohesion, where they counted drops of oil, detergent, and alcohol that would fit on the surface of a penny. I think the penny was able to hold the tallest bit “drop,” but the penny held the highest number of individual drops of alcohol.
4. Capillary Action, where they timed how fast liquid would travel up a piece of paper (this one was kind of a dud, and didn’t work out very well; I’ll change it up next time).
5. Fun with Ice, with two activities: First they explored how ice floats in freshwater vs saltwater (I forgot to take pictures, but I’d filled water balloons with water the night before, so they could float them in buckets of water). Then they explored how dye behaves when dropped onto freshwater vs saltwater ice. We’d started this experiment at the end of class the previous day . . . each group filled one dixie cup with freshwater, and one with saltwater, and we left them in the freezer overnight. This part of the experiment was SO COOL – you can really see how the dye behaved differently. It slid right off the top of the solid block of freshwater ice, but little pockets of brine in the salt water ice allowed the dye to seep in:
6. Surface Tension, where they made boats that were powered by detergent. (More on this in a bit)
Overall, the lab was fantastic! It took about 2 hours, 15 minutes for them to get through all the stations, and they didn’t seem to run out of steam before the end. It also really reinforced for me the importance of having these hands-on experiences. As I wandered around the room, listening in on their conversations, it was cool to listen to them talking/working through concepts in a way they never have to do with a lecture-only class. I love teaching the lecture-only class, because I do think it’s a great way to reach a lot of students in a relatively short period of time, and I do my best to give them some cool experiences outside of class, but WOW – the students do get a lot from doing labs like this.
After lunch, we had the most fun of all: the Detergent Regatta! I challenged everyone to come up with the absolute best design for a detergent racing boat. At stake was a top-notch prize: their choice of rubber duck from my amazing array of colorful little rubber ducks.
Here are the boats:
Get ready, get set, RACE . . .
After several races, the overall winner (Ryan M) chose this adorable ducky:
We ended the day by taking a submarine tour through the cell (which I then reinforced with a lecture on the most important points). Here’s the video I use (although in class I show a version that I edited to take out some of the cell function stuff that we haven’t covered yet).
Before showing the video, like I said up above, I put the entire class through a shrink ray (which consists of me flashing the classroom lights on and off real fast by making a shrink ray noise – think a sort of electrical humming). I always tell them to REMIND me to unshrink them at the end of the lecture – it could be tragic if any of them ventured out of the classroom before being returned to their normal size ahhhhhhahahahahahaha. 😀