I found this article while searching Pinterest and thought I would share. It's a tutorial on how to lock your iPad so your toddler will stay in the app that you open for them to play in.
J is constantly clicking out of it or opening something he shouldn't play in and then gets mad because his game is gone, so this is definitely a life saver for when we let him use it.

Re: iPad tip for toddler use
Thanks for this.
It's amazing how many apps are open when I get the ipad back from B.
BFP #2 5/27/12. EDD 2/1/13. m/c and D&C 6/21/12.
This is our problem with J. He can swipe to other apps and I have no idea how he does it! We only let him use the iPad for special occasions but it is irritating to both him and me when he swipes it to the next app and he can't figure out how to fix it.