How Do Biologists Estimate Population Size?

estimating-populationThis activity introduces to population biology by showing them the mark-and-recapture technique (also known as the Lincoln-Pearson method ) of estimating the size of a population.   The activity requires some set-up to create bags of “animals” that will be used for marking and capturing.  Bags can include small items like beans or pennies, or small plastic toys.

The activity describes the steps involved in the technique where students “capture” 10 animals and place marks on them with masking tape.  They then release the animals back into the population and  trap samples randomly.  A mathematical equation is used to then estimate the number of the entire population.  Students can then either count the number of items in their bag or the instructor can keep a key with the number to compare the real value with the calculated value.

Grade Level:  8-10  | Time Required:  45-55 min


HS-LS2-2 Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems of different scales.

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