[ExI] 5th Grade Science Fair -- Evolution

Kelly Anderson kellycoinguy at gmail.com
Sun Mar 25 02:55:41 UTC 2012

Friday, I went to my son's 5th grade science fair. It was really a lot
of fun watching these young kids get excited about experimentation. My
son was chosen to progress to the district (no surprise there, we have
been working hard on our experiment) and is very excited by the

So, here was his experiment (OK, I helped some)

We got a bunch of wingless fruit flies. The control group just spend
their life in a plastic container with food. The experimental group is
introduced into a terrarium with a tree frog. After 24 hours, the
survivors were picked out of the terrarium, and bred in a new
generation. The process is repeated until there are enough flies to
create a new generation. Repeat.

The hypothesis was that there would be some differences in the group
exposed to the natural selection of the terrarium habitat and frog. We
did not hypothesize what the differences might be, we just hoped we
would be able to notice.

I expected that we would have to break out some pretty heavy duty
statistical math to determine if we had results worth writing home
about because evolution is supposed to be slow. Well, we were
certainly wrong about that.

We spent a lot of time observing the flies. Interesting little
creatures, much more entertaining than the frogs. The fruit flies have
this habit of always disbursing from each other rapidly, as well as
climbing up the sides of the little cups they are kept in. Kasey
noticed that the first generation survivors seemed to go faster than
the control group. So we set up a video race, raced the two groups a
couple of times, analyzed the video, and indeed, the first generation
was moving at approximately 1.4 times the speed of the control group.
The second generation went 3.7 times as fast on average. Now this
isn't to say that the individual flies are all that much faster, but
the ones that sat on their butts at the bottom of the cup seem to have
not survived very well (go figure).

We were astounded that the results were so pronounced. Perhaps my math
is wrong. Kasey is going to double check my figures, but they are
noticeably much faster just looking at them.

Evolution is fun. And by no means is the selection part necessarily
slow. It only took about two and a half months to get our results.
Most of that time was spent allowing the few survivors to reproduce up
to suitable numbers for testing and generating the second generation.

This has been a heck of a lot of fun. The only down side is that I've
discovered the life expectancy of these particular frogs is over a
decade! And they grow to about 4 inches long. Don't know if I can
produce enough fruit flies for frogs that size!! :-)

Compared to the average 5th grade project, this is quite involved. I
think he'll go far in the competition. We will have to see.


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