Need help on the control for the Marble Machine experiment

[deleted-406201]

What is the control to the Marble Machine experiment?

[deleted-362338]

Hello mace5300,

I am assuming you are talking about the following project:
https://www.sciencebuddies.org/science- ... p051.shtml

Control variables are essentially things that you are not changing about your environment, experimental setup, and/or measurements. That way, you can freely change one variable (independent variable) and measure its effect on another variable (dependent variable). In this project, the control variable(s) are different depending on what you want your independent and dependent variables to be.

For example, if you were to change the size of the spheres in each trial and measure the amount of spheres that get sorted into each group, you would want to have everything else unchanged (e.g. the size of the holes the spheres fall through) so that you can see how the size of the spheres affect the number sorted. Similarly, if you wanted to see how the angle of the grate (see video: https://www.sciencebuddies.org/science- ... #procedure) affects the speed of the sorting process, you would want to only change the angle and keep everything else (e.g. the size of the spheres) constant to correctly measure the relationship.

So the easiest way to determine your controls is to first determine your independent and dependent variables and then see what you need to keep the same to ensure your dependent variable is not affected by anything other than your independent variable.

Here's more information on variables if you still need help:
https://www.sciencebuddies.org/science- ... bles.shtml

Good luck and feel free to write back with any more questions!