Hello. On the homework for my middle school chemistry class, one of the questions asks me to identify "the four classifications of substances". I am having difficulties with this problem.
I can classify matter many different ways so this is like looking for a needle in a hay stack. One way follows but I don't know if the author of your problem was thinking of this classification.
Perhaps you mean states of matter; solids, liquid, gases which is the old standard of three. Then plasma has been added to make it four and a fifth recently as the Bose-Einstein Condensate state