We have been considering how to control what students are doing while working on a Samsung Tablet. I checked out Mobicip which can be downloaded from Google Play and it is good but it will cost you a nominal amount per student.
Here is an article that explains how to tweak the tablet so that your charges can only access what you want. This will even help the parent who hands his two year old an android device and watches in horror as the child hammers on random icons. Check out www.techradar.com/news/mobile-computing/tablets/how-to-make-android-child-friendly-1045708