Mixture of definitions and concepts -- often, just reading through the "taboo" words acts as review. I tended to use this as a de-stressing review activity before a midterm. It's good vocabulary review. I used it for all levels of high school chemistry (special education and ELL through honors).
For me, this was good for first quarter midterm review, though the individual chapters (intro to families/Periodic Table, intro to safety/general and atomic models/history) are color coded so you could split this up if you really wanted to...
Works best in groups of 4 (two teams, A and B, of two each):
1. Team A Player 1 gives clues to Team A Player 2, trying to get them to say the bold/underlined word WITHOUT using any of the descriptions listed below.
2. Team B Player 1 keeps time, while team B Player 2 looks over the shoulder of Team A Player 1 to make sure that none of the "taboo" words are spoken.
3. Each card is a point. Try to accumulate as many points as possible within each round.
4. A the end of a round (I recommend 90 second rounds), any clue that was not guessed gets randomly shuffled back into the deck. Clues that were guessed correctly are taken out and become point markers.
5. Next round: Team B Player 1 gives clues to Team B Player 2, while Team A players keep time and make sure none of the forbidden words are spoken.
6. My class rule was always: no skipping allowed. If you accidentally say a "taboo" word, the round is over.
7. An additional class rule (for me) was always: everyone has to take turns giving and receiving clues.