At best, scientists are only able to estimate population sizes. One means of estimating population numbers is a sampling method called the line transect method. This involves determining a species' distribution area, dividing it into smaller sections of equal size, and only counting actual animals in a small section. When counts are taken in several of the small sections, an average number of animals per section is calculated. The Raisin Reasoning activity will give students exposure to the concept of population sampling.
Procedures Divide the students into groups of three.
Have them wash their hands. Explain that it's impossible to count the exact number of a marine mammal species because we can't see into the water and because animals move from place to place. Population surveys are done by sampling methods. Observers count animals actually seen in an area. Based on that sampling information, they estimate the entire stock or population.