Yellow
Green
Blue
Red
Magenta
Remove
Tag the Bats. Work with your team to capture and tag exactly 250 bats from your cave. That is, take 250 beans from your bag and tag them by making a mark on both sides of each captured bean with a marker. Then, put the tagged beans (bats) back into the bag (cave). Mix the tagged beans with the untagged beans in the bag. Be sure to mix them well.
Sample the Bat Population. You will collect three different-sized samples of beans: small, medium, and large. For each sample size, you will repeat the following procedure four times:
- Collect a sample of beans from the bag.
- Count the number of tagged beans in the sample (t).
- Count the total number of beans in the sample (n).
- Record the number of tagged beans (t) and the total number of beans in the sample (n) in a data table.
- Return the sample to the bag and mix the beans with the rest of the beans in the bag. Mix the beans together well.
Note: You will take a total of 12 samples—four samples with a small scoop, four samples with a medium scoop, and four samples with a large scoop.
As you work through this simulation, it is important to keep in mind that you have much more control over the beans than scientists have over bats existing in the wild. For instance, a few beans may drop on the floor as you work, but you should notice that and be able to find them quite easily. In nature, there are many events that cannot be controlled as easily. Some of the bats can leave the cave through openings that the scientist is not aware of, the tagged bats may stay in one part of the cave so that they are not mixed well, some may be eaten by predators, some part of the bat colony may move to another cave, and some will die. In lab situations, we can see patterns and trends and make approximations of total populations with greater certainty than we can when we study animals in nature.