Beginning students can definitely can get in to the bad habit of looking at there fingers every note they play. I know first hand I did myself as a kid. This can definitely be a bad habit to break especially if no one corrects it. There are a variety of ways to solve this problem, but I have had much success with just a piece of paper.
I don't just hold a piece of paper over a students hands and tell them to play, I make it FUN! What better way to fix a bad habit then making it fun and not even realizing your breaking it!
What I do with that single piece of paper is fold the two sides of the paper so that they can easily slide in between the keys. then I have the student put their hand underneath the paper so that they can see there hand. But instead of just having a blank piece of paper on a students hands you can have your student color it or design it any way they want. Even make it a score board on so they can keep track how many times they get a certain part right!
If you don't have the time you can always check out Music for Little Learners model to cover you hands and just print a copy!
For more fun and exciting ideas during piano class check out musicforlittlelearners.com