What is does control group and experiemtal group in the experimental design mean?

i'm gonna assume you've got water in with the bakin' soda seeds an' some in with the apirn' seeds too

if that's the case then your control group would be the seeds with just water
in order to be able to call them "control" though, you'd hafta make sure all other conditions are kept exactly the same as the other two groups

the indep var is what you manipulate i.e. bakin' soda n' asprin' which have diff pH levels
so i guess really your IV is pH, and the number of days (time) you also are manipulating

the DV is what effect that pH has on your seeds
DV=dependent variable=experimental group