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The sun is beating down today and so we are thinking about solar energy. We are actually thinking about going to the pool but at 112 heat index inside in air conditioning writing a unit on solar energy is a bit saner.

In the early 1830’s a British astronomer made a solar collector to cook some of his food during an expedition to Africa. However using solar energy goes back to earliest human dwellings. In New Mexico there are cave dwellings on the north and southern facing mesas. The North facing caves are assumed to have been for the summer months when the angle of the sun’s rays was more direct and the air temperatures were hotter. The south facing caves were believed to be used during the colder winter months.  This use of solar energy by moving to colder spots or warmer spots was probably common with nomadic folks.
You can track the angle of the sun’s rays by keeping track of where the sun is on a southern facing window in your school. Just have a student go to the window each day at the same time and place a sun sticker where the sun is on the window. That position will change throughout the school year and it will amaze the kids that the sun is really not moving but we are. That piece is a difficult one to teach but there are some resources out there.
http://solar.physics.montana.edu/ypop/Classroom/Lessons/Sundials/sunpath.html
http://starchild.gsfc.nasa.gov/docs/StarChild/teachers/sun_motion.html
It is not the sun’s apparent motion that is going to become the focus of my unit. I am concentrating on good old solar energy. The interest began when I went to a local battery shop and saw a solar cell phone charger. I bought one to see if it works and then searched the web and found tons of great activities where kids build or dissect solar energy cells.
The “Build it Solar” site probably has the largest list of projects. Some require more than I want to get into.
http://www.builditsolar.com/Projects/Educational/educational.htm
The most likely project for my unit will be the pizza box solar oven.
http://www.nmsea.org/Curriculum/4_6/pizza_box_oven/pizza_box_ovens.htm
There is a lot of ground to cover before we ever get to the build. I will want my students to calculate the solar energy in our area and to learn some simple metric conversions while we do that.
http://www.wunderground.com/calculators/solar.html
Next, we will need to understand a bit about energy and how it is transferred and how it is put to use. There are hundreds of sites that cover that ground. I will keep it pretty basic.
http://www.eia.doe.gov/kids/energy.cfm?page=solar_home-basics
http://www.energyquest.ca.gov/story/chapter15.html
This will give the kids a chance to put their kinetic molecular knowledge to use and understand a more dynamic system. We should cover both passive solar systems and photovoltaic. The passive is simple but the photovoltaic is a bit more complicated.
http://www.howstuffworks.com/solar-cell.htm
The key question we will pursue in the unit is whether or not it will be cost effective to use some solar energy in our school. We can look at passive and at photo cells that transform sunlight into electricity. One school is using solar powered vent fans in the top floors to help cool a building in the hotter months. Another redesigned the school entry way to collect heat in the day and move it about with fans in the evening.
http://www.nrdc.org/greensquad/library/energy_solar.html
http://www.crestonesolarschool.com/about_us.html
So, as the solar energy continues to heat up my corner of the world I will use that time to get a bit more informed about how to use solar energy to teach more interesting science.  I consider that a good use of a very hot day.

 

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