Learning Critical Thinking Through Astronomy, Week 8

This post is being written one week late. That seems to be a pattern and I need to stop it.

The first class day of this week was devoted to finishing up some WebAssign assignments related to the shadow activities. There are STILL some students who have not completed these activities but I have given up on motivating them at this point. There’s only so much I can do, and only so much I can be expected to do, to help them.

The remainder of the week was devoted to constructing the celestial sphere kits. If you’re not familiar with these kits (developed at Harvard as part of Project STAR) most of this point probably won’t make much sense to you. The kits actually contain parts for a celestial sphere, a working telescope, and a working spectrometer. The second and third items are used in second semester astronomy.

These celestial spheres take about ninety minutes to construct from start to finish. One time consuming part is cutting out the star charts that must be traced onto the inner surfaces of the plastic hemispheres. I’ve eliminated this step by having a supply of pre cut star charts available in the classroom. Students use these and “dontate” the new charts from their kits to me, ensuring that I have a perpetual supply of them for future clases. With that problem solved, the most time consuming part is now the actual tracing.

There are many places where construction can go wrong:

  • Students can trace the same star chart (half of the sky) onto both hemispheres.
  • Students can not align the end points of the ecliptic (they don’t know that name yet…we just call it “the arc” at this point) with the end points of one of the ridges on a hemisphere.
  • Students can trace the star charts onto the outsides of the hemispheres instead of the insides.
  • The paper strips representing the calibrated ecliptic (calibrated with dates and constellation names) can be installed backwards or upside down.
  • The paper strips can be installed with too little tape to securely hold them.

I’ve seen all of these before, but this semester everyone seemed to do quite well with the assembly. The MWF section only meets for one hour on Wednesdays so they obviously didn’t have time to complete the assembly so they did so on Friday. Both the evening section (MW) and the TuTh section completed assembly in one class period with some time to spare.

Now that everyone has a working celestial sphere, we can spend next week (a short week due to fall break) learning the parts of the Earth/sky system or as I call it, the anatomy of the sky.



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