I am doing a Catalase lab (Enzymes)

I don't understand this question:

What are the controls in the experiment?

1 answer

What things could alter the outcome of the experiment?

Some possibles, which may not all be relevant are:

Temperature?
Gravity?
Pressure?
pH?
light level?
ionic strength of solutions?
dissolved O2 level?
glass or plastic apparatus?
how was apparatus cleaned?

If you organised these types of things to be constant throught the experiment or between experiments then these are controls you have imposed.