Remember the first day , at least, you are going to want to be the winner of the score board. You can make it a tight race if you have a good class, but set that in place from the beginning.
The rewards for the scoreboard can be both free and simple. How about 1 minute of free talk time at the end of the period? How about king of the hill or an academic game for 3-5 minutes...The beauty of the scoreboard is that you can decide...YOU are in control!
Let us know how it goes for you!
Welcome to teacher HEAVEN!