Students need to match the adjectives with their opposite. Words could be deleted to make it more difficult.
Game 1 - place cards face down, students have to find the matching opposites. When ever the student turns over the card, they have to make a sentence with the adjective.
Game 2 - stick one set of opposites on the wall/around the classroom. Call out an opposite and the students have to run to the right matching adjective. Students could also make sentences with adjective in the positive/negative/question form. Eg. She is thin/ she isn't thin/ is she thin.