Flash cards can be used in various ways with young children. Simply put them out and show your child how to look for matches – in this case, a match would be finding the opposites. For an older child, you can also use them like a memory game with the cards turned over and set out in lines.
Kizclub.com has good printable flashcards for working on the concept of opposites. You can also do the traditional flash card game by holding up a card and asking your child to tell you what would be the opposite. It might be helpful to first look at all the cards together and go over the opposites.
If your child makes mistakes, use encouraging statements like, “Good try, but that one is the opposite of ____. Can you see any other pictures that might be the opposite of ___?” “How about this one?” Allow your child enough help to feel successful. Research shows that kids learn faster and retain more if they are having fun. In time, the concept of looking for opposites will become easier.