Explain that present whale populations are difficult to estimate, and that estimates of the original populations of whales are not much more than educated guesses. The International Whaling Commission, the only worldwide organization with any responsibility for controlling the whaling industry, bases its population estimates on sightings and the number of whales caught compared to the effort involved. Explain to students that they will be recording the number of whales sighted on four different days. Use three types of beans to represent three whale populations. Shake the box back and forth and place on overhead projector.
Students count and record what they see.
Ask students to describe the difficulties in counting. Ask them what they think are some problems in trying to count whale populations. After 1st sighting, tell them that it's time for bed. Kids will sleep and snore, etc. Next day, they are back on the ocean.