Buoys are used to help lobstermen find their traps. They are usually attached to either end of a string of traps. A string can hold up to forty traps, but it is most common to have from fifteen to twenty.
Before starting to make the buoys, have the students decide on the colors for their buoys. Make a classroom key that matches buoys and lobster harvesters.
To construct a lobster buoy, tape an empty toilet paper roll to the mouth of an empty half-gallon plastic milk jug, then have the students paint their buoys with their chosen colors. (To make the paint stick to the plastic, try mixing a little liquid detergent with the tempera paint.)