That was Not a Solar Array - nor a useful exercise




I got an email about some free classroom resources available through the National Research Council of Canada (Link).

Now, I know that I've been going on a bit about how the web over-promises. I have a whole post called Online Resources - Few and Far Between wherein I quote a disgruntled colleague: "You click on a link, and it just takes you to another link, and then another... and you never get to the thing they promise."

Yet.... In my increasing desperation to show that I'm a Team Player, I went ahead and clicked the link they offered.

*sigh*

Well, okay. It took me to a pretty interesting looking web page full of science pics and yet more links. I scanned it, deliberately avoiding the "class projects" or "fun things to do at home" bits, and settled on a hotlink that promised "assessments."

The assessments button took me to a second web page, but there were no assessments. Hmmm.... Oh! But here's a "for more" button. Maybe that's where the assessments are...

*click*

A third page opened, this one offering three topic areas (and making no mention of assessments at all!). I chose Outer Space (I think they called it Astronomy and Space Science).

*click*

A fourth page - fourth page! - opened to offered yet another list of topics. Well, "subtopics" I guess. I chose Solar Energy.

*click*

A fifth page opened - assessments are now long forgotten - to reveal a short paragraph on solar power and space travel, another on the solar array used on the International Space Station, and then a brief description of a class project - you remember how careful I was to avoid class projects - involving tin cans, heat from the sun, and a pinwheel.

*sigh*

Well, okay. Maybe it was my fault. Maybe I got off track. Maybe there really was an assessment section somewhere, and I missed it.

How about this solar energy stuff? Was this bit of science any good?

No.


NeT.

Negative.

Houston, we have a problem.

You see, the "experiment" - grandly titled Make Your Own Solar Array - is about learning that warm air rises, and rises with some force when pushed through a chimney. (The air inside a chimney of tin cans painted black spins a small pinwheel.) That is, it displays thermal energy (heat) being converted into mechanical energy (mechanical motion).


But the ISS solar array uses a photoelectric process that converts light to power. It doesn't work off of sun-warmed air. In fact, thermal heating is a problem for the array; see International Space Station Thermally Induced Solar Array Base Loads.

Worse, this distinction - between thermal based energy and light based energy - is not explained on the web page. There's a real possibility learners will be confused into thinking the ISS uses heat energy.

At least, I was confused. Maybe the ISS really does use thermal warming to generate power, I thought, and spent 20 minutes on the NASA site to clearing things up.

I am a team player. I am. But I think, sometimes, I'm on a different team.



~~~~~

National Research Council of Canada:

The International Space Station will capitalize on the Sun's energy. This is evident by the size of the solar arrays. These panels will focus the rays of the Sun and harness the energy into a usable form.

NASA:

Power will be generated for the International Space Station by utilizing the energy of the Sun. The Sun’s energy will be absorbed by eight solar arrays. These eight solar arrays make up the four large, flexible photovoltaic (photo: light; voltaic: producing electricity) modules. Modules are made up of silicon-based photovoltaic cells, which generate small currents of electricity when exposed to energy from the Sun. These modules will produce approximately 240 kilowatts of power, which is enough to run 60 average-sized homes.

Incidentally, NASA doesn't do any better when it comes to teacher resources. They also follow a short piece on the ISS and its light-energy array with a school project using thermal-energy. See NASA's From Sunlight to Power: International Space Station Solar Arrays.


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