A straw in a glass of water appears to be broken because of refraction. I looks like the pencil is broken because the light bouncing of the pencil refracts, or bends as it goes in to the water.
![](http://1.bp.blogspot.com/-AiUiLgMCCts/TaOKeTYiznI/AAAAAAAAAgc/gvwVa1W-S7U/s320/IMG_0583.jpg)
We also had fun playing with lenses.
A convex lens is shaped like this.
A concave lens is shaped like this.
![](http://4.bp.blogspot.com/-adKjmG-VStY/TaOLL58_L-I/AAAAAAAAAg8/G4MynJWqcbE/s320/IMG_0593.jpg)
![](http://4.bp.blogspot.com/-dFWAyojh8Qw/TaOLLrbQccI/AAAAAAAAAg0/mzdq8d1CV5I/s320/IMG_0592.jpg)
![](http://1.bp.blogspot.com/-0ylxUQAmNIk/TaOLLLoP8aI/AAAAAAAAAgs/Su2ja7RoUVI/s320/IMG_0591.jpg)