Science

Safety glasses or goggles protect the eyes in a laboratory. Sometimes a face shield is used on top of those.
Goggles
Safety goggles and safety spectacles.

controlled variable

Albert Einstein

The dependent variable in this experiment would be the type of paintball marker. You must make sure you keep the other variables constant. Meaning using the exact same barrel, propellant and paintball types. If you use different setups on each, you have not proven that the marker itself was the key determining factor.

You would test your hypothesis by predicting what the results of your experiment will be so it's like a type of prediction. Another way is what do you think the outcome will be.

An example is the flame test, a method of qualitative analysis.

Which statements are true of all scientific endeavors

One false statement would be that we can go warp speed.