Divide your class into two teams. Tell students that a representative from each team will come to the front of the room and identify parts of speech in various sample sentences.
Have the two representatives hold a magic wand each behind their backs, and turn to face the screen. When you display the slide, the first student to tap the correct part of speech with his or her wand is the winner; that representative continues to play, and the losing team replaces their representative. Continue playing in this manner until you run out of sentences.
You will have to establish a few ground rules. Tell students to be gentle with your wands and the screen, or you will end the game. No fighting over wands (and believe me, they will, especially the boys) and no arguing with your judgment calls about the winner of each round. If you have to, you can stop the game early and give them a really boring worksheet to use; this will put an end to future squabbles over the game.
This game is ideal for filling time, because you can play for as little or as long as you like. Your students get to practice their grammar and you get a little break in your day. It's a win-win situation.