Last week I posted about how to simulate counting populations using the “Capture-and-Release-Method.” (Click here to see!) This week, continuing on the population theme (and using dried beans in the classroom), I wanted to share a population extinction game!
I found this activity on tes.com, which is a site that contains many different lesson plans for teachers. And it is free to register! Click here to see the lesson (although you may have to sign up to actually see it).
The activity uses the Wild Atlantic Sturgeon as an example population, however you could adapt it to any type of animal you would like. The link directs you to the instructions for the game, and a simple game board – a paper with boxes numbered 1-6. It also includes a chart where students can record their data.
- Instruction sheet, game board and data sheet (can be downloaded for free from the website!)
- 20 small items of something (I used beans, but the instructions say paper clips)
- A cup of extra items for each group (they may need more!)
- Give each group of students 20 beans (or whatever you chose to use) to start off with.
- Students toss/drop the 20 beans onto the game board
- Any beans that land on sections 1 and 3 are considered “extinct” and are removed from the game.
- Any beans that land in section 5 “reproduce” so you add another bean for each.
- Beans that land on any of the other squares are kept with no changes.
- Students record their numbers in the chart provided, then repeat steps 2-4 with any beans they have left for 10 total rounds.
Over time, students should notice the amount of their sturgeon slowly declining!
Discussion questions to use:
- What years did you gain the most?
- What years did you lose the most?
- Did your population of sturgeon become extinct? Why are why not?
- If so, how many years did it take?
- Why do you think your population declined?
Just how do scientists know how many deer live in an ecosystem? How did they figure out the number of giraffe live in the African savanna? Where do ecologists get these numbers from?
These are some of the questions that my class discussed while studying changes in population and population density. Students guessed how this was accomplished: using satellites, sending people out to look around a lot, catching some of the animals and then bringing them back to the wild, looking at a small area, then estimating.
Although some responses seemed more on track than others, I wanted students to simulate one way scientists do this! The capture-mark-and-release method is the one we chose to try. And because I already had a bag of dried beans from a different lesson, that is what we used as our population!
- Dried beans (these represent the “animal”. You can also use dried pasta, packaging peanuts, or another low cost, small item that can easily be marked)
- A bag or other container
Before beginning the activity, I had divided up the beans into cups for each group of 2 to 3 students. I did not count the number, but used a few handfuls.
I created a chart for students to use like the one below
Estimating Populations Chart
- Students first grab a handful of beans from their cup and mark each one that they removed with a marker. Count how many beans were marked and record this on the chart.
- Return the marked beans into the container and shake the beans.
- Grab another handful of beans from the container.
- Count how many total beans are in the new sample, and then how many marked beans were in the sample. Record both numbers on the chart.
- Using the formula below, students calculate how many beans are estimated to be in their container.
- Repeat steps 3-5 again, recording the numbers on the chart.
- Once students have recorded the data, the group can make one final estimation of how many total beans they believe to be their container.
- Finally, students count the number of beans they have and compare this number to their estimations!
How does this simulate what scientists do?
Those that study population densities of different organisms will often use this method of capture-count-and-release. A group of organisms is captured and marked with a device or tag. Later in the year, or the following season, scientists will capture another group of that organism and see how many have been previously tagged. If there are only a small number of tagged organisms, scientists assume there is a larger population. If many of the organisms already contain tags, then the total population may be quite small. By using the bean simulation, students can begin to understand this process!
Questions to discuss:
- Compare the bean simulation to real life. What is alike and what is different? You might bring up that beans do not die or give birth, so the population will remain static (as long as no beans get lost under the table!). Live organisms always have changing populations, so this would affect the number of organisms in an ecosystem.
- How precise is this method? When students compared their estimations to the actual number of beans, they found that some groups were pretty close in their estimation, while others were not. We noticed a pattern of groups that had marked a higher sample initially also had more accurate estimations!
- Can this be used for all organisms? When I asked this question, students in my class determined that this would be very difficult to use for types of insects or other very small creatures. Larger animals would work better!