iPad's are used for tests in my school and students are using them to cheat. Any suggestions?

My students are using a lot of the native iOS features (splitscreen, dictionary, different gestures) to cheat during tests in their classes. I have caught students using a splitscreen and opening their notes or photos to get information to use on a test. Some teachers have caught students using the dictionary feature when holding down on a word. Some teachers in my school are already wary of certain issues the iPads bring, but this is really deterring teachers from moving forward using the iPads for assessments. I mainly use Google Forms, but there are some of our curriculum websites as well that are being used for assessments.

Does anyone have any suggestions on how to address this? Or is Apple making any kind of "test mode" iPads can enter that would disable these features?

Any input would be greatly appreciated!