The class should form 4 groups.
For each station, devise a sampling (not a census) experiment that you can do in 5 minutes to try and figure out the desired percentage.
Each group will have 7 minutes total with each station.
Use your time effectively - if you finish early, try and redo your experiment (the more trials the better), or do another experiment.
Take notes on your group activities and prepare to present your work to the rest of the class. Explain your experiments and results. Critique the problems and biases in your sampling experiments.