Estimating the number of fish that return to spawn using capture-recapture methods.
It consists of a large bowl (about the size of a 5 L mixing bowl) and a supply of small beads (about 5 mm in diameter) in two colors. [In the simulation experiment outlined in the paper, you will need 4,000 green beads and 400 white beads.]
A sampling paddle is used to select a sample of beads. This looks like a large
pancake flipper with the base of the flipper drilled with 100 cavities (width 6
mm; depth 3 mm).
When this paddle is pulled through the beads, the holes are
filled with beads. The student can very quickly count the number of beads of
different colors and is assured of a sample of 100 when all the cavities are filled.