It sure does. Anything more than about 5 minutes is aerobic.
You could try either. Low Impact will be gentler on your body the next day (initially). The advantage with step is that you have your own step - which means your own personal space with limited chances to collide with anyone else.
Whilst learning, stand sort of in the middle of the room, near to the back, but not the back row. DO NOT STAND AT THE SIDE OF THE ROOM!!! You will be facing all directions at some point, and if you're at the side, you will be looking at a wall, which isn't helpful. Position yourself so there are people around you in all directions. so you have someone to look at.
Often when you start out, it can be easier if you find someone near you in the class who looks like they know what they're doing, and follow them to some extent. The instructor is usually on a stage, possibly facing another direction, possibly demonstrating a different move - confusing!!. It really can be easier at times to not look at the instructor.
Hear the beat. Aerobics is activity to music. The music is not just there to sound good, but it provides the tempo and the cue. Four - four time. 1234,1234,1234,1234..... learn to hear the beat and life becomes much easier.
Focus on learning the names of the moves. Try and learn two or three names every class. Possibly even write them down afterwards. Aerobics is much easier when you can rely on your ears, and not worry about what you see. After a while, good participants can do a class simply from hearing the beat, and the name of the move (assuming the instructor is on beat
Wear what's comfortable. Depends on your climate and whether your gym is air conditioned. Loose t-shirt or singlet. Shorts do not have to be loose. The current style of knee length shorts is good if you don't want them to ride up.
I agree with the earlier comment about wearing basketball shoes instead of running shoes for better lateral support (Air Jordan basketball boots are the greatest aerobics shoes ever made). However, as a beginner this is much less of an issue and running shoes will be ok initially. When you become more proficient, then consider different shoes.
Remember - aerobics is like anything else... it takes time to learn, and the learning process can be unpleasant at times. The rewards can be huge if you stick with it.
Never give up, never walk out of a class because it's too complicated. Never feel initimated by the instructor or by other participants. It's YOUR workout, the instructor is only there to give you ideas....
Good luck, and let us know how you go!
Barry Watkins AFAC instructor Brisbane, Australia