Does a spinning class fixed wheel bike affect real world form? I just had my first spinning class and hadn't realised it was going to be a fixed gear bike, when the instructor was asking us to get out of the saddle (or half out) the necessary technique felt very unnatural and much more 'bouncy' than what I would do climbing a hill on a road bike. 
Does that mean bad things about my real world form or are they just very different things? And if so will a lot of spinning change how I ride?
The exercise bike feels different, because it is fixed in place and can not react to your movements like a real bike.

When you jump out of saddle, your body moves forward in relation to bike. On road, the you keep moving at roughly same speed and the bike slows down momentarily to accommodate the change in relative positions. A fixed exercise bike can't move, so you are moving and stopping instead and that is what you feel as jerking motion. Also, when standing on a real bike you rock the bike to keep your body in place, but since this exercise bike does not allow sideways motion you have to move your weight sideways to put force on pedals.