Solar hot water project/competition

We will be building our own solar hot water heater. We will work on this in class on Friday. Each student is responsible for building a solar hot water heater. You are responsible for bringing all the materials but many could be made from recycled materials. For example, you could make it from plastic bags, glass, plastic, or metal bottles, or cans.
Things to consider: Dark colors will absorb more sunlight than lighter colors. Insulation will keep it warm on a cool day. We will hold the competition on a sunny day next week. This will be announced the day before in class. You must be present that day to set up your hot water heater.
Rules
1. Must hold and heat 300 ml of water at least 10 degrees Celcius to earn credit.
2. Must be passive solar powered. This means you can not use photovoltaic power, electricity, fossil, or nuclear fuels.
3. Must be small enough to fit in your locker.
4. The warmer your water gets the more points you will earn.
5. First place in each class gets 50 points extra credit, 2nd place gets 25 points, 3rd place gets 10 points.
6. The person with the highest temperature achieved from all my classes will earn 100 points extra credit.
Only one entry per person. If you make more than one, you have to decide which one to use on the day on the competition.

If you start now, you can make and test several models to see which works best.