## Thursday, July 05, 2007

### Learning about variables with digital cameras

Below you'll find a couple of the projects from the Online Science Fair that took place in my classroom this past spring (2007). They are actual photos that students took to show what the variables were in their experiments.

Question: My question is, when you drop a 3 ounce ball from 4 inches above, does a spoon fling a marble higher if the leverage is smaller?

Hypothesis: I think that if the lever is smaller then the marble will fly higher.

Variable: My variable is the different notches on the spoon.

Results: My results were that if the lever is closer to the end of the spoon, the marble will fly higher.

This is a great experiment on the position of the fulcrum of a lever and the lever's resulting strength. Since we did not study levers this year, this student never learned the associated vocabulary. But with this simple photo, he has illustrated his variable.

Question: Does the size of a marble affect how fast it sinks?

Hypothesis: If the marble is smaller, then it will sink faster.

Variable: small, medium, large, and extra large marbles

Results: I leared that the more mass an object has, the faster it will sink. The big marble had more mass, so it sank faster.

Once again, a great experiment where the student has learned about something that we did not study in class this year. Also once again, this simple photo has illustrated his variable.

Next Year

Looking at these photos, I realize how much they will help me next year. I can easily use the marble photo to teach variables. Imagine the following problem:
• Dave wants to see which size marble will roll the farthest down a ramp. He takes three books and places a cardboard ramp on top of them. Then he takes four marbles of different size (refer to the photo) and rolls them down the ramp one at a time. He measures the distance each rolls. What is the variable in the experiment?
• Referring to the photo, ask students what changed in the experiment.
• Then show the next photo. Here's the scenario: Kerry wants to see if the length of a string a affects the speed of a pendulum. He measures three pieces of string (12 in., 18 in., and 24 in.) and creates three pendulums with them. He then swings them and counts the number of swings for 10 seconds. What is the variable?