Prizes and punishments are part of controversial topics for teachers and many teachers see extrinsic material rewards as an appropriate and effective way to manage behavior in the elementary classroom. Other teachers don't want to bribe their students to do work that they should be intrinsically motivated to do on their own.
In my classroom if a student does something well or I see that they should be rewarded for something I normally give the students a homework pass to use on a missed assignment or an assignment they forgot to turn in and this seems to motivate students to get a homework pass and keep it fair for students who don't get one. If homework passes aren't used and saved till the end of the semester they can use it on their final for 5 extra points.
Other incentives that I use in the classroom are educational computer games that I put on the smartboard if they finish their assignment they can play a game till the end of the period. If you have any suggestions or incentives that work in your classroom please post below.