A Mini-Lesson

THE NATURAL SELECTION
OF BEAN HUNTERS

Author Unknown

EVOLUTION

 SYNOPSIS

 CONCEPTS

 MATERIALS

 STUDENT HANDOUTS

TEACHING STRATEGY

See Procedure in Student Worksheet (below)

It was not clear what was intended by (step 4), when a group becomes extinct, the instructor "will distribute the extinct students". This could mean that the students in the extinct groups would be distributed evenly into the remaining groups. But this seems a little illogical, and could be confusing or complicated (as to providing appropriate tools, etc.). Might be better to just let them take up positions on the periphery of the hunting area, or go sit on a bench. Try different strategies here, let us know what works for you (see "Feedback" suggestion #5 below).

Somewhat more elaborate versions of a multi-generation simulation can be found at "The Chips are Down: A Natural Selection Simulation", or Thomas Atkins' "Bebbledwark World".

FEEDBACK FROM A USER: Some useful suggestions...
From Deborah Thomas in Danville, CA (Thanks a bunch, Deborah).

We just did the "Bean Hunter" lab in my high school biology classes and I'd like to share some thoughts and suggestions.

First of all, the lab is terrific. The kids had fun and really learned the concepts.

Suggestion 1: The lab needs a graph showing the number of beans that survived and how they multiplied with each generation.

Suggestion 2: I referred to the students as hunters. We divided the class into clans that were named by the hunting "tool" they used. (Can't say weapon these days.) So: Fork Clan, Glove Clan, Hand Clan etc.

Suggestion 3: Instead of tape, we used inexpensive cloth work gloves - but I turned the thumb inside out so the hunters had no opposable thumb! We also used plastic forks, knives and spoons and bare hands. Each hunter was issued a "tool" and a plastic cup.

Suggestion 3.: We referred to the beans as "prey". We used different colored beans because they were available. We called them: The long toothed white bean, the red butted killer kidney beans and the sabertoothed black beans. The kids enjoyed the names.

Suggestion: 4: Bring a small white-board outdoors to keep tally of the results. This gives the students a way to copy the data.

Suggestion 5: Students who become extinct can sit down, work on their data tables and answer the questions.

Suggestion 6: To be more efficient, I measured the bean volumes in a graduated beaker (or grad. cylinder) instead of counting them. For example, 140 black beans filled approximately 40 mls. This sped up the "seeding" process considerably. (I did have the students actually count the beans they captured. Using the ml. beaker made my job easier.)

 ATTRIBUTION

Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.

1. Original Source: unknown participant in ENSI or SENSI

2. Reviewed / Edited by: Martin Nickels, Craig Nelson, Jean Beard:

3. Edited / Revised for website by L. Flammer 3/1/99

 Name_________________________________ Date___________ Per.____

PURPOSE: To experience how the principle of natural selection works.

MATERIALS: paper cups, data sheet
Tools: knives, forks, spoons tape, bare hands
Beans: yellow beans, white beans, green beans

PROCEDURE:
1. Divide class into five groups of six. Each group receives a different tool which represents its set of genes.

2. Class goes outside to grassy spot where 200 beans of each type (total of 600 beans) are dispersed.

3. At signal, class will collect beans for 3 minutes, count them, and record data by groups.

4. Instructor puts data on master data sheet (see data sheet overpage). The two groups with the least beans become extinct. Instructor will distribute the extinct students [not sure what this means; use your imagination; try different things with the extinct students!].

5. For each color, the number of beans that remain in the grass will be doubled and added by dispersal in the area.
Example: 50 green beans collected from 200. This leaves 150, therefore add another 150 making the new total 300. Do the same with the other colors.

6. Repeat two more times (two more generations) so only one group is left

QUESTIONS:
1. Which groups became extinct first, and why? (what tool were they using?...what else might have contributed to their extinction?)

2. Why did we double the number of beans that were left uncollected?

3. Did any bean group become extinct? If so, which one(s)?

4. How does this experiment relate to naturally occurring animals, e.g. birds, for example?

5. What is a good trait for a bean seed in this experience, and why?

6. What is the best suited trait in this experience, and why?

7. How might a group of organisms in nature avoid extinction due to competition? (Hint: Darwin's Finches are a great example).

8. Write a paragraph about this experience, pointing out how it illustrates the elements of natural selection.