A chess system is a complex of opening positions that can be played almost regardless of what is thrown at it.
The hedgehog is one such example. You seem to be on the right track.
Chess systems came into the forefront of chess theory in the 1970s. The triangle against QGD systems, various offbeat Indians (1...c6, 2...g6, 3...Bg7 4....d6) and so on are all "system" openings.
Kings Indian Attack?
I think the difference between an opening and opening system is that in a sytem it's less relevant what your opponent does.
Like the london opening or KIA (as scott mentioned)
Yeah, the KIA is an example also.
Generally, these systems should NOT be recommended to novices because it encourages lazy thinking. The chess coach and the student both tend to fall into a one-size fits all mode of operation.
The video I watched on the London system was more about key development and which pieces are good to get involved. For instance, getting the black bishop involved for white early, after a queen's pawn opening.
Regarding not worrying about what black does, I know the KIA and how white can vary any of its move order to achieve the desired position. Can there be a lot of openings like this?
I think the reason you haven't heard much about systems before is that the concept is somewhat vague and not terribly useful for players at the level you are coaching. The idea behind using an opening system is to steer the game into a position where you will be more comfortable than your opponent. I sort of do this by playing the English, 1.c4 rather than 1.d4 or 1.e4. However, depending upon Black's response, the English can lead to a fairly wide variety of position.
I don't think that it is a good idea for high school players to be thinking in terms of systems, mostly because their playing styles are not developed sufficiently for them to know what systems are particularly suited to them. In order to improve, you need to learn to take what the position offers, whether it is opening the position and attacking or trading down to an ending if that is where the best chances lie. I think that an inexperienced player who is always trying to force the game into a particular type of position is going to hinder his own development.
That is not to say that there is anything wrong with a high school player using the London System as White if he likes it, but I would caution against looking for opening systems that can be played regardless of what the other player does. If your opening moves don't vary in response to your opponent's moves, it probably means that he is being given a lot of freedome to do whatever he wants.
I've been coaching chess and learning the game for about 8 years and only recently have heard of chess systems. I've read a bit about them and from what I have read, here is what I think:
the chess system is a plan of general themes: development, getting pieces developed, etc. Then, certain openings with more "set/book moves" can fall into a certain system.
Am I way off base?
Thanks
Neil