Provide each pair of students with 20 index cards, and have each pair divide the cards evenly between them. Then provide each pair with ten vocabulary words. Tell each student to write five of the words on index cards, one word to a card. Then tell each student to write the definitions of those five words on the remaining five cards, one definition per card. Mix up the cards, turn them upside down, and place them in five rows of four cards each. Have Player 1 turn over two cards. If the cards are a word and matching definition, the player keeps those two cards and continues his or her turn. If the cards don't match, they are turned back over and Player 2 takes a turn. Play continues until all words are matched to their definitions.