Oh my gosh you guys I've been so busy! I mean, there's the usual home, family, crafting stuff. Plus helping family move, plus getting Max ready for kindergarten (next week! eek!), plus end of summer adventures. I also finally have a teaching job, so I'm prepping classes and classrooms like crazy. Matt's also been really busy with work, so I was feeling kind of bad this weekend. Like maybe Max wasn't getting enough of our time and attention.
But however bad I feel, I still have to get stuff done, so I pulled out some favorite standby activities that we don't do all that often. Max enjoys these every time, and his reaction to them has changed over the years, which I think makes them even better. When we did these when he was 2 or 3 years old, he just enjoyed the colors and the mess. As he's gotten older he's gotten more interested in what's happening and why, and they've shown their colors as early science experiments as well. Best of all, you probably have everything you need for these at home! These are great little activities to pull out at a moments notice, but there are real scientific things happening here that you can explain to your budding chemist. Disclaimer: I myself am not a chemist. But I did double check my knowledge on these, so I'm not totally off base. ;D
The Classic: Vinegar and Baking Soda
What to do
This chemical reaction has been the standby of elementary school volcanoes for a long time, but there are lots of way to play with the combination. One of my favorites is to cover the bottom of a plate or pie tin in baking soda. Then I mix white vinegar with a few drops of food coloring in a couple of different cups. Then Max, armed with a disposable pipette, drops the vinegar onto the baking soda and watches as colored fizz ensues. Small squeeze bottles, eyedroppers, etc also work great. Or even just a spoon!
For little ones, just tell them it's a cool chemical reaction. As they get bigger here's the details: the acetic acid in the vinegar reacts with the sodium bicarbonate in the baking soda to form carbonic acid. Carbonic acid then (quickly) breaks down into carbon dioxide and water. All those carbon dioxide bubbles popping is what gives you the fizz. Cool!
The New Favorite: Milk and Detergent
What to do
This one is especially pretty with all the colors used. Max often wants to repeat this one several times before moving on. Take a pie tin (like the one just used above) and pour a layer of milk in the bottom. It doesn't need to be deep, and every type of milk I've tried has worked at least a bit, though 2% works best. Then I give Max the food coloring bottles and he drips colored drops into the milk in whatever designs he wants. If you don't want to give them the whole bottle you can give them little pools of color and have them drip it with paint brushes. Finally, give them a toothpick dipped in detergent (dish soap) and have them poke different spots in dish and watch the colors rush away. Try dragging it around! You can make some cool patterns and colors this way.
Well, since the food coloring is less dense than the milk it sits in place instead of immediately dissolving. When the soap touches the milk, it begins to dissolve the fat molecules which lowers the surface tension of the milk. The unaffected milk has a higher surface tension which pulls away, dragging the food coloring with it. This makes it look like the color explodes out from where you touch. You can repeat a few times until there's enough soap in the milk that surface tension if fairly even throughout the pan. Rinse and repeat!
The Messy Monster: Cornstarch and Water
What to do
I actually already talked about this one awhile ago when I posted about Kid's Party Games. For the little ones, I'd make it yourself. Start with a bowl of cornstarch and add water a little at a time until you get a slime consistency, then add your color of choice. Now that Max is older I have him make it himself so he can see how it changes with the water additions. When you hit the perfect ratio it's really very cool. When touched gently or poured it will flow like a liquid, but when hit or dropped it resists more like a solid. Plus it's squishy and messy and generally fun. (Bonus: it cleans up really easy!)
Ready for a fancy word? This cornstarch-water-combo (called ooblek at my house) is a non-Newtonian fluid. This is because it acts differently when subjected to different forces, as you saw. The ooblek acts this way because the cornstarch isn't dissolved in the water like when you make salt water, it's suspended in the water. So it's really just a lot of solid molecules snuggled up next to liquid molecules. When poured, it acts like a liquid because the molecules all flow along together. If you punch it, the starch molecules are forced up near each other, trapping the water molecules in between them, so it reacts like a solid.
When you're ready to get really fancy, show your kiddos how non-Newtonian fluids dance! It's quite something:
Okay, hopefully those will be as much fun at your house as they are at mine! And everyone enjoy gearing up for school!