Guided Access 

If you have a student who finds it difficult to stay on the app that you are asking them to work on it is possible to lock them into an app using guided access. You need to set either a passcode or finger recognition on the students device. This works best on apps but if you are using a web based program such as Math Fact lab or Handwriting Without Tears you can choose areas of the iPad to block access too.  This means you can block off the ability to open a new tab or click into an old tab.