Many students nowadays think that if their parents do not know then no one will but that is not true. There is a vast amount of both resources that can be found in their local library or even their daily search engines. If students want to get additional reviewing after a tutor session they can easily type in the title of the lesson they are having difficulty with and get some information of how to prepare for a test and some ways they can solve a problem without giving them answers (simply as guides). If they are not good with use of technology- they can simply ask their tutor in helping them explore some additional guides on top of what their tutor covers to ensure they are ready for the next big test.
For example Mathslice.com can help generate worksheets for themselves with practice questions they could use as extra practice in their math and Purplemath.com can help with step by step instructions to act as an additional guide for their children. I myself use this when tutoring in Math subjects as it provides an additional review for them when I may not be there to help them.
Now these sites are only to act as additional resources and last minute review when tutoring has concluded and they just want to complete some last minute exercises and see how they do.