A good exercise to get an understanding of opposites.
Preschool Game - Little Matchups Opposites is a very good app for kids to improve their understanding of opposites. The concept of the game is simple, the kids have to match the cards that show the opposites of each other. The app offers 32 different opposites. Before the kids start, they can choose, with how many cards they want to play and what kind of opposites they want to train. If they touch the card, they will hear the named opposite.