A reflection that would receive .7 points

A reflection that would receive .9 points

 
 

1. This is similar to what people have written after a discussion of static electricity.
 
 

Yesterday, for about the millionth time, I got shocked when I got out of my truck and went to close the door, and after our lecture on electricity, I think I know why.  I think that when I slide into and out of my seat, some of the electrons move from the upholstery to me, and I end up with extra electrons. This is similar to the build up of electrons on the rubber rod when it was rubbed with nylon in lecture. These extra negative charges wouldn't tend to stay near each other (like charges repel), but they have nowhere to go.  For instance, even when I get out of the car and step on the ground, those electrons don't flow into the ground, because my shoes are made of rubber and act as electrical insulators.  This is static electricity, because there is a build up of charge and it is not flowing. This is similar to the build up of electrons in the electroscope as we saw in class. When I lean over to shut the door, the extra electrons finally have somewhere to go: they jump from me jump to the metal of the car, which is an electrical conductor, and I feel this as a shock.  As we learned in class, the tiny bit of light you sometimes can see with a shock like this is just like lightning, and the sound is the tiniest sound of thunder!  Amazing!

After working out the details of this situation in my mind, I tried to teach my brother how this works.  First, I had him slide out of the car and touch the door.  He was shocked, and I asked him why.  He thought something was coming out of the car to shock  him, so I asked him why he thought he didn't get shocked when he just touched the car while he was sitting in it.  He was stumped, so we tried several things: him sliding out of the car while holding on to the roof the whole time (no shock), sliding out and walking away without touching the car (no shock), and getting out of the car without sliding (no shock).  We concluded that the sliding was important, and that he needed to touch the car with his feet on the ground afterward in order to get a shock.  I used little circles of paper to represent electrons, and I showed how he picked up extra electrons as he slid and then how these jumped from him to the car as he touched the door.

Sample Scoring
Diagram:  .1
Photo: 0
Description:  .2
Connection to Class:  .2
Creativity: 0
Extended Application: .1
Outside Research of the Concept:  0
Curricular Connections:  .1
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Total:  .7

2.  This is similar to what people have turned in after the discussion of energy.

     After our lecture on energy, I started thinking about alternative energy, especially wind power.  I have always been interested in sailing, so I decided to see if I could make a model sail car that would run on wind power.  I used a small piece of wood for the body, thread spools for the wheels, chopsticks for the mast and sail supports, and tissue paper for the sail.  I used a lot of hot glue to get the mast right, and the wheels were attached with screws through the center of the thread spools. I was careful not to screw the screws too tight, as I wanted the wheels to turn with as little friction as possible.  (Friction would cause a lot of the energy from the wind to be converted to heat, rather than to the kinetic energy of the car.)  To test my car, I put it on the floor and blew a fan on the sail.  The car went really well until it got too far from the fan!  I thought about the fact that the energy that made my car moved probably began as solar energy which was stored in plants long ago. These plants died and changed into the coal that was used to run the power plant which supplied me with electricity.  The electricity was used to turn the fan blades, and the these made the air move, which, finally, hit my car's sail and made the care move.  The car would have continued in a straight line at a constant speed (due to its inertia), but it was acted on by an outside force -- the force of friction with the floor and air.  So my car's kinetic energy was transformed into heat energy in the floor and in the room.

     I also did some research to find out how wind power has been used in the past and found that there is evidence that wind has been used by people to do work for at least 4,000 years.  There is direct evidence that Persians were using wind power to turn mills to grind grain by 600 A.D., and it is estimated that there were 500,000 windmills in China and Europe at the beginning of the nineteenth century.  Some areas where the wind is consistent are setting up 'wind farms' to generate electricity with windmills.  There is no pollution with this, and the land can often be used for other things such as farming and ranching at the same time! *

* Source: “Wind Power: Clean Energy for Colorado,” accessed 10 January 2002, available from http://www.cogreenpower.org/

   This topic has a lot of connections to the curriculum in other areas.  I used measuring and other math concepts (such as dividing by two) to get the wheels and sail spaced evenly.  Alternative energy is a big political issue now (e.g. California's energy crisis last year), and so this topic is also related to the social studies curriculum.  If I had students make cars like this, I would encourage them to decorate them (art) and possibly create ads for their wind-cars (language arts and information skills).
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Sample Scoring
Diagram:  .1
Photo: .1
Description:   .2
Connection to Class:  .2
Creativity:  .1
Extended Application: 0
Outside Research of the Concept:  .1
Curricular Connections:  .1
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Total:  .9