Diameter of the Sun
Poke a small hole in a large card or piece of dark construction paper.  Hold it in sunlight about three feet from a piece of paper so that a small image of the Sun appears on the paper.  (You will probably get better results if you have someone help you.)  Measure the distance between the card and the paper and carefully trace the Sun’s image on the paper.  
We can set up the following ratios:
Solving for the Sun’s diameter we get:
Write up a description of how you accomplished this project and include the data that you collected and your calculations.