In the following vignette, Barbara, Doug, and Karen use a model to continue their discussion of the nature of science and its implications for the teaching of evolution.


"Thanks for meeting with me this afternoon," Barbara says. "To begin this demonstration I first need to ask you what you think science is."

"Oh, I had that in college," says Karen. "The scientific method is to identify a question, gather information about it, develop a hypothesis that answers the question, and then do an experiment that either proves or disproves the hypothesis."

"But that was one of my points about evolution," Doug says. "No one was there when evolution happened and we can't do any experiments about what happened in the past. So by your definition, Karen, evolution isn't science."

"Science is a lot more than just supporting or rejecting hypotheses," Barbara replies. "It also involves observation, creativity, and judgment. Here's an activity I use to teach the nature of science."

Barbara takes a cardboard mailing tube about one foot long that has the ends of four ropes extending from it.

As Barbara tugs on the various ropes one at a time, she has Doug and Karen make observations of what happens. After three or four pulls, she asks Karen and Doug to predict what will happen when she pulls on one of the ropes. Both are able to predict that if Barbara pulls rope A, rope B will move. Barbara then asks if there are additional manipulations they would like to see, and she follows their requests.

Barbara then asks Doug and Karen to sketch a model of what is inside the tube that could explain their observations.

When Karen and Doug show their sketches to each other, they realize that they have come up with different models. Barbara asks them if they want to make any changes to their sketches based on the comparison, and both of them make modifications, although their final models are still different.

Barbara then gives them their own cardboard tubes and some string and asks them to build the model they proposed. When their models are built, Barbara holds up her tube and asks Doug and Karen to follow her actions with their own models, to see if the two models behave in the same way as Barbara's tube. But when Barbara pulls string A in her tube, Karen's model does not work the same way. Karen asks if she can make some changes in her model, and once she does her new model seems to work the same way as Barbara's. Doug's model consistently behaves the same way as Barbara's tube.

"Now wait a minute," Karen says. "What do ropes and tubes have to do with science and evolution?"

"You might not know it, but what we just did is much of what science is about. You observed what happened when

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