Friday, March 23, 2012

More Fun With the Afternoon Class

I don't really have to do anything in particular with the afternoon class, which makes it really fun, but also challenging since I led high with the space rovers!! I don't want to let them down with something lame!

 Week 2 I bought a bag of dry-ice (check your local supermarkets- our Harris Teeters sell blocks by the pound.  Buy a little more than you think you'll need and wrap it in a kitchen towel to keep it cool.  You CANNOT put it in  your fridge or freezer, it'll freak out your thermostat and break it.  If you have a cooler, you can use that, but keep it slightly propped open so that it doesn't pop off.  Since Dry Ice is literally solid carbon dioxide gas, when it "melts" it lets off gas.
 We did several fun experiments.  First, we put a piece of regular ice on paper towel, and a piece of dry ice.  This was to prove that when Dry Ice "melts" it is changing from a solid to a gas.  We talked about how things typically have to change phases from a solid to a liquid to a gas and that skipping from a solid to a gas is called sublimation.  Then, we needed to prove that the gas being released was carbon dioxide.  We talked about how carbon dioxide smothers fire (which is really just rapid oxidation) and then lit a candle inside a flower vase.  When you put a chunk of dry ice next to it, the flame is smothered.  Then we did some fun stuff- dry ice in hot water (which makes lots of steam!) to show that the gas is leaving (mark the water level on the cup before adding the dry ice) and nothing is added to the water.  We also showed the difference between a mixture and a solution.  By adding food coloring and dish soap to water and then adding the dry ice, you can make regular bubbles because the food coloring is not changing or reacting with the bubble solution.  You will make lots of bubbles.

Finally, we made ice cream.  You need to use a bowl fully 3 times as large as the amount of liquid you have.  We used a pint of heavy cream, an individual serving of strawberry milk, 1/2 a cup of sugar, and 1t of vanilla (mainly so I'd have more jobs for kids).  Before you start your experiments, place a 2-3 inch square of dry ice inside 2 heat duty Ziplock bags.  DO NOT SEAL ALL THE WAY (remember that gas? they'll pop!).  Then beat the dry ice until you have a very fine powder.  Be diligent! You don't want a child biting down on a piece of dry ice! You'll make instant ice cream when you add the powder and stir.  You'll notice I used too small of a bowl! The ice cream tastes a lot like an ice cream float because of the carbonation you're adding to it.  The kids loved having a taste.  I don't let them eat more than a spoonful each, but they enjoy the whole process!
 This week, I decided that we'd do tie-dying.  There was no real point to this.  We even made tie-dyed snack by spreading colored frosting dots with toothpicks.  I used canned frosting.  It was gross, but the sugar addicts seemed to enjoy ;)
 Decorating graham crackers.  It's intense work!!
To make these shirts, you insert a dixie cup under the top layer with the open side of the cup facing up.  Place a rubber band around the cup, and then draw a design with sharpie markers.  Designs with LESS area covered, like dots, stars, or small dashes, do the best.  After you're done drawing, drop rubbing alcohol over the area (the cup catches the excess) using eye droppers or straws (put the straw in the cup, put your finger over the top opening of the straw, release over the shirt).  
Here's thing 1 in a shirt he made at cub scouts the same way.  We first tried this technique at the Children's Museum near the Outer Banks, and it's really really fun and a fairly clean way to tie-dye!!
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