I agree with the bio and physics. People criticize lab assignments for being boring and unscientific (largely the case only with a bad TA and bad methodology wherein it is partially YOUR fault if you "disprove" gravity in your lab). However, if you flip the thinking a bit, it is boring because you understand the working pieces of it. You learn, in a visceral way, that science is a thing. A thing that you can do! I remember our lab (with guidance, obviously) group derived the procedures for counting the population of a bunch of unicellular organisms just by thinking about the problems and the possible solutions. My experiences with TAs may be unique, but I think if you come at them the right way, there is a lot of value to be had.