TechIntersect

It was pandemonium in the Clyde, KS city park last Saturday as more than 40 kids took part in Clyde’s first ever Science Fun Day. Designed for kids in grades K-3, but fun for kids of all ages, there were animals to see and pet, rockets to launch, sticky goo to play in, and much more.

While DelRay Capper and Katie George helped me lead the activities, the project was documented by the children themselves using new Flip video cameras that will soon be available for checkout at the Clyde Public Library. These cameras are so simple to use that even a small child can operate one successfully. The videos they made will be compiled, edited and posted for viewing on the Clyde website at www.clydekansas.org.

With a national shortage of science, technology, engineering and math workers that is only expected to worsen, having activities like the Science Fun Day becomes ever more important to help with the problem. I was especially pleased with the number of young girls who participated. In contrast to a longstanding stereotype about girls in science & mathematics, a recent NSF study found there are no significant differences between girls and boys scores on standardized math tests. Parents, it’s ok to encourage your young girls to explore math and science careers! With a national shortage, we can no longer afford to discriminate against women in these areas. I think it’s important to get all kids thinking about these careers.

When we asked what the favorite activities of the day were, many replied that they really liked the baking soda and vinegar rockets, and the cornstarch goo. Many of the kids were asking me how to repeat these experiments at home, and since they were mostly household items, I can share with you here how some of these are done.

Rockets

To make a fun and simple rocket find an empty plastic 35mm film canister, the clear Fuji Film kind work best. Open the canister and pour a small amount (1/2 tsp) of baking soda into the lid. Now pour a little vinegar (1 tsp or less) into the canister. Quickly snap the lid onto the canister so the vinegar & soda can react together. Set the canister lid-side down and back away. Be sure to do this experiment outside, because these rockets can shoot up in the air 20 feet high! When the baking soda (a base) and the vinegar (an acid) combine, they produce carbon dioxide gas that pressurizes and eventually pops the top of the film canister.

Cornstarch Goo

With the right combination of water and cornstarch, you can mix a batch of goo that becomes a non-Newtonian liquid. Isaac Newton said that liquids only change viscosity by varying temperature, and for most liquids this is true. Just think about how pancake syrup thickens as it gets cold or how it becomes runny when warmed. However a non-Newtonian liquid such as cornstarch goo also changes viscosity with pressure. Applying sudden pressure causes the molecules to align into a temporary solid arrangement. Release the pressure, and it becomes a liquid again. When you have the right mix of water and cornstarch, you can roll it into a doughy ball, like play dough but when you stop rolling it, it becomes a liquid again right in your hand.

The kids had a lot of fun with this experiment because it was so messy. I saw kids, sticking hands and feet into it, and even jumping and running on it with bare feet. This one is also messy and probably best for outdoors, but when the goo dries, it hardens into a cornstarch residue that can be easily washed away or swept up.

Diet Coke Geyser

This experiment was made famous on internet sites like YouTube. Drop a packages of Mentos candies into a 2 liter bottle of Diet Coke and stand back! The foaming soda shoots high into the air out of the bottle. Scientists believe that this is a physical, not a chemical reaction. The carbon dioxide gas is trapped inside a mesh of water molecules in the Coke. The candy breaks the mesh and provides lots of nucleation sites where CO2 bubbles can rapidly form, allowing the pop to come shooting out of the bottle. It is essentially the same as what happens when you violently shake up a bottle of pop. The molecular mesh breaks and the tiny bits of CO2 can join together and rush to the surface. If you have no Mentos, many other items can have the same effect. We successfully used ice cream rock salt for our experiment.

Merry-go-round

I’ve been showing Emily and Thomas the merry-go-round trick for several years now. Conservation of angular momentum is a physics concept easily demonstrated on the playground using a merry-go-round. A group of kids piled into the center of the merry-go-round will turn faster than the same group of kids hanging out on the edges. Spin the merry-go-round then have your kids move in and out again so they can change the turn rate. We didn’t discuss the idea in the park, but the same thing happens as the Earth orbits the sun in the solar system. When the Earth is closer to the sun, it is moving through space faster than when it is farther away in its orbit. Comets experience this even more dramatically, speeding up as they approach the sun and slowing to a crawl as they enter the outer reaches of their orbits.

For a first-time event, I think we can call this a success. I’m really looking forward to trying this again next summer and will be on the lookout for new ideas to try. In the mean time, I will try to get the videos posted soon so everyone can see what fun we had at Science Fun Day 2008.

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