Wednesday, January 26, 2011

Weather Science Round 1

I have a dear friend who teaches my kids Spanish. We were talking portfolio review stuff and she happened to mention that she finds it tough to make time for messy science experiments.

We are all about messy science experiments!

I also realized that a lot of the fun messy science stuff for younger kids had fallen by the wayside as my older kids did fun messy (dangerous) science experiments while the little ones were otherwise occupied (you know, watching Bob the Builder).

The obvious solution was to do a little science class for her kids and my younger kids with the older ones working as lab assistants. We had the first class on Tuesday.

I decided to start with weather since we are having a lot of weather. Nothing like teaching current science events: Hey! It's cold out! Why is that?

We started with an explanation of the seasons (this requires a dark room): Klenda held the Sun (a lamp with a bare incandescent bulb (don't use a florescent bulb for this). Zorg held the Earth (globe) at the appropriate tilt and orbited (walked around) the Sun while all the Zoomlians sang, "The sun is a mass of incandescent gas..."

Now that it's stuck in your head too, back to class: I had put a dot of clay to show our location, so it was easy to see - Hey! We aren't getting much sun! Look! Australia has all our sun! The North Pole was completely dark and the South Pole was completely bright.

We went on to show that "not much sun" was only part of the reason we are so cold right now. I had the kids hold their hand flat (palm facing the "sun") about 6" away from the bulb. That felt pretty warm right away. Then I had them hold their hands at the same distance, but at an angle. The near part felt warm, the part angled away felt almost no heat at all. With our part of the Earth angled away, the little sun we are getting is much weaker than our summer sun.

What else makes us cold in the winter? Wind! And what makes wind? A very clever guess was "The rotation of the Earth." That's partly true, but not the main reason. The big answer is: the sun! Yes, we're all about that "gigantic nuclear furnace" here!

It's true: most wind is caused by the sun heating the atmosphere. Warm air rises and expands, cooler air sinks and shrinks. To show warm air rising, we took some warm bubble juice outside (I had gotten a party pack of little bubble bottles and set them over the oven to warm). We used our warm air to blow bubbles and... voila! They rose. A bit, anyway.

It was nice to have it 43 degrees, after so many frigid days, but it made this experiment less dramatic. Leena came up with a good twist that saved the day. She made some bubbles by blowing (mild upward flotation) and then some by swinging her arm. The bubbles made with ambient air dropped like rocks! See! Warm air rises!

And that was the end: 30 minutes that Klenda complained felt like 15, never a bad way to end a class. Tune in next week when we will make clouds and rain...indoors!

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