Help with Independent/Dependent Variable Biology question

The question is: A group of students are working to see whether or not caffeine increases speed on the 100-meter sprint. List the independent and the dependent variables. Please help? Explain?

The independent variable is treatment with caffeine, some participants are treated with caffeine and some are not. The dependent variable is running speed. It is dependent because it is postulated that speed can be influenced by caffeine, the independent variable.

independent is always what is manipulated
in this case the amount of caffeine you give the racers

dependent is what changes as a result of the manipulation
in this case the time on the race

you need something to compare against to give validity
so you would need runners with no caffeine to race too

and record their time as well as the drinkers
you would want very accurate measures and records of how much caffeine to who

all the students working on the project would need to make sure they did things exactly the same way

records would need to be expressed in a way that anyone could duplicate the experiment

independent variable: caffeine levels
dependent variable: speed of 100 m sprint.

independent is something you would change..so your changing the caffiene levels (to see if there is a difference from no caffiene)

dependent is the effect of the independent variable....so if you did/didn't change caffiene levels...would it affect the speed of the sprint