Saturday, December 20, 2008

How to Teach Altitude

This blog was supposed to be How to Teach Altitude and Using the Clinometer.

But I'm thinking now that it just needs to be How to Teach Altitude.

So, the point of teaching the "Altitude in the Sky" concept is getting kids thinking of the sky as an upside down bowl. Altitude and Azimuth are the Latitude and Longitude of the sky. The altitude of a star is how many degrees above the horizon it is. The azimuth of a star is how many degrees along the horizon it is and corresponds to a compass direction.

There's more to it than that, but I don't think middle schoolers need to worry about the Celestial Equator and such.


Get your students back in the big circle around your room. Make sure different students are at the cardinal points on the compass (N, S, E, W). Of course, if you wanted to, it wouldn't hurt to review azimuth for a couple of minutes.

Then, go stand in the center of the room. First introduce the ZENITH of the sky.
Does anyone know what the very top of the sky is called? No matter where you are, it's always directly above your head. NOT where the brad is on the Star Wheel, (if you've made Star Wheels) but the very center of the oval that is the night sky. It's right above your head. That's right! ZENITH! (or tell them if no one knows.) What's the place below your foot called? Where you are standing? That's called NADIR.
Then talk about the HORIZON. How there always is one, and how this is where the moon and stars come up from hiding in the Southern Hemisphere as the Earth turns on its axis each night.

Once you have ZENITH and HORIZON established, hold one of your arms over your head pointing at the ZENITH. Stretch your other arm straight out toward the HORIZON. Wiggle your upraised hand.
What is it pointing toward? You got it! ZENITH.
Wiggle your other hand.
What is this one pointing toward? That's right. HORIZON.
Now, how many degrees have I formed with my two arms? Yes! 90 degrees? So what degrees would you say the HORIZON is? Yup. Zero degrees. And the degrees for the ZENITH? You got it! 90 degrees!
Have all the students imitate you. One arm up toward the ZENITH and one arm out toward the HORIZON.
And where are you standing? Does anyone remember that? Right! NADIR! (Wiggle your 90 degree hand.) And what is this pointing toward? Right. ZENITH. (Wiggle your 0 degree hand.) And this? Right. HORIZON. (Just say this next sentence, don't demonstrate!) Raise your HORIZON hand to 45 degrees. (Wait till most of them have it.) Half way up, right? Try for 30 and 60 degrees. (Demonstrate the concept of one-third up from the HORIZON is 30 degrees and two-thirds up from the HORIZON is 60 degrees.)
Point to 85 degrees. Point to 15 degrees.(Do several more.)

What about 45 degrees at azimuthal 0 degrees? (You are previewing "coming attractions" here.) Can you all point to 3o degrees at azimuthal 90 degrees? (You might say nobody point yet, five seconds to think about it, count down immediately, 5-4-3-2-1-0 Point!) This gives the slower ones time to think. Stops them from pointing where the smarter ones point.
Move on to USING THE CLINOMETER or move on to another topic, something sit-down, if you wish.

Come back tomorrow for USING THE CLINOMETER.

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