I am a professional painter, my wife is an art teacher. There are a few
products out there that can remove paint.
COMMERCIAL STRENGTH WINDEX
Ammonia is a carrier in paint. Dried paint on the other hand is very hard to
get out. But DIRTEX will remove dried paint to some extent without staining
or bleaching clothes. What I would suggest is that you mix a soap and water
solution, 2 to 1 and put it in a spray bottle. As soon as the paint hits the
clothing, put the soap and water on it. Soap keeps paint "alive" so it can
be washed out. I'd suggest a change of clothing at school, so if by chance
you stain a favorite article. You can soak it and wash it out later.
Hope this helps