Science Buddies: "Ask an Expert"

I am working on building model bridges. I am building stress tests to measure weight capacity. Is there a control variable???

Hi brennanclh,

Welcome to the forum. Reading about variables will probably help you: https://www.sciencebuddies.org/science- ... bles.shtml

It sounds like weight capacity will be your dependent variable -- that is, you're going to build several different bridges and see if their differences cause their weight capacities to be different, right?

Your bridges can vary in lots of different ways: they could be made of different materials, be of different shapes, be of the same shape with different thicknesses, etc. If you have two bridges that are different shapes and made of different materials, then you don't know which difference caused the change in weight capacity, do you? That's why you pick one variable to change, the independent variable. Every other thing that could possibly be different about the bridges as well as about how you carry out the tests and measurements should be kept constant -- all of those are control variables.

Amanda