The fact is that there is little you can do to control what students do while they are taking a quiz. We recommend that teachers:
- Randomize quiz questions by shuffling questions and/or responses
- Make their tests open book, open notes (students can refer to them during the test)
- Set a time limit on the test
- Consider making the exam "proctored" (students take the exam while being observed)
- Consider de-emphasizing the importance of tests (it's less tempting to cheat if the stakes are lower)
- Consider creating alternative assessments (papers, projects, case studies, etc.) instead of using tests to measure students' knowledge
There are also lock-down services which can be purchased and integrated into Moodle.