Last week I was at a family camp retreat with, not surprisingly, my family, amongst others. We go on this particular retreat most summers and this year I volunteered to keep the kids entertained for a hour every day. I got a group of four kids, including my own, that were all in the 7-9 age range. I've volunteered for this job many times over the years, and this time came in armed with a plan that we would do science experiments. I've learned that coming in married to an itinerary, curriculum, or really any fixed notion of how this thing is going to shake out is pretty unrealistic, but this time it went off swimmingly. I had a great batch of kids, and we had a lot of fun and generated a good deal of noise and mess. I had a good friend who signed up to help me without knowing what I was cooking up, so props to her for hanging in there with me with the noise and mess.
I thought I'd lay out my week's worth of activities here, and in case you someday find yourself facing a group of wily small people that look like they might eat you if you show fear or make a false move.
Day 1: Nucleation Sites
I wanted to start of with something impressive to establish my creds as reasonably cool for an adult, so we went with a classic. Mentos and Diet Coke. If you need a break down of how the science works, check out this simple explanation. I ran the experiment once, then broke down what was going on, and then we ran it one more time. If I had had one more bottle of diet coke, I would have poured some out into glasses and let the kids stick their fingers (or leaves, or rocks, or whatever) into the cups to show that you needn't be a piece of candy to provide the carbon dioxide with a nucleation site. You need a two-liter bottle of diet coke, about 5 mentos, and big open outdoor space to run this thing. And while it's not necessary, this inexpensive gadget both makes the geyser more impressive and helps you get out of the way of the impending fountain a little faster.
Day 2: Potential vs. Kinetic Energy
I started this one off by raising up a ball (I actually used a piece of fruit) and dropping it to talk about the idea of potential energy and kinetic energy. Then we got to the fun part and make marshmallow catapults out of popsicle sticks. This was a huge hit. I used this model for our project (minus the painting) and it worked great. A few notes, try to buy modestly sized rubber bands. The long ones just need to be wrapped that many more times, which is tricky for small hands, and if the rubber bands aren't tight, this project literally isn't going to fly. Also, it's a really good idea to glue a bottle cap or something to the top of the stick to hold the marshmallow ammo. For little hands, holding down the main lever plus keeping the base solid on the floor is tricky enough. If the marshmellows go falling off the end before you fire, it's can get frustrating. I had intended to glue bottle caps to a handful of sticks with hot glue before I left on my trip and plum forgot. I made do with elmer's glue and it was insufficient. We grabbed a handful of spoons from the dining room and substituted those for the upper sticks when the caps started popping off, and it worked fine, but sticks and caps would have been better.
Once the catapults were constructed, I handed around marshmellows, spread some targets around on the floor (I liked this one and this one) and let the kids have at it. A natural place to take this one is Newton's Second Law of Motion. If I may humbly suggest, don't hit the kids over the head with this one. In ten minutes they'll be there on their own, goofing with squishing the air out of the marshmellows first, or mushing a bunch together to see if it will fly farther, or pushing down harder on the catapult level to see if the marshmellow goes further or faster. I prefer to wait until they start asking the questions to give them the answers.
Day 3: Acids and Bases
Vinegar and baking soda is always a big hit. We talked about the differences between things like lemonade and orange juice versus things like milk. Then I gave each kid a bowl and a couple of cups of flour. They had fun making volcano-shaped receptacles while I walked around distributing the baking soda. (I began explaining about how this isn't how actual volcanoes work, and one of my eight-year-old proteges was right there with an explanation of tectonic plates. We shared a a very floury high-five.) Then I gave them a cup of vinegar and away we went. I had brought food coloring along thinking to let them choose the color of their not-a-real-volcano reaction, but two of my younglings were wearing pretty white dresses that day, so the coloring stayed safely unmentioned in my bag.
Day 4: Surface Tension
On the fourth day of science, we made bubble snakes and talked about surface tension and the polarity of water molecules. Before I even brought out the bubble materials, I got a group of kids to be water molecules wandering around at random until they bumped into each other and joined hands. Then I introduced an air pocket into the mix (modeled by my co-conspirator and lovely assistant) wandering into the middle and until all the little water molecules had formed a circle around our foreign object. Many giggles were had, and then we brought out the bubbles. No white dresses today so we got to play with food coloring. My hands were blue and green for two days but the kids had a good time.
Day 5: Wind Power
This is the only activity I bought as a kit, rather than foraging for the necessaries around the house. We built balloon-powered helicopters. I used it as an opportunity to review potential and kinetic energy and we talked about how the blades are shaped to take advantage of the air currents we were creating and about how that's similar to how windmills work, so that was good fun. The kits weren't expensive, but also not very durable. We had cracked blades at the end of 30 minutes and several balloons popped right out of the box. Even though the kits came with extras, I wish I had bought an extra bag of party balloons at the grocery store. The kids had a lot of fun, but I think out of all the activities I tried last week, this is the one I'd drop were I to do it again.
At the end of the week, I asked the kids what their favorites were, and the soda geyser from Day 1 was the over-whelming winner. So when it doubt, blow something up. (Safely.)