What are take-home exams even for? I've been a flight instructor since 2010 and I've never once given one. I can't see any possible value in them.
Students' unsupervised time is for discovery and practice. "Here are some questions. The answers are in FAR Part 91. Read the Part, answer the questions, we'll discuss them next class." Or, "That concludes computing wind correction angles. Here are some practice problems just like ones we've done in class today, take them home, work them yourselves, get comfortable with this process. Questions?"
Exams are for determining the students' current knowledge and abilities. What ability does a take-home exam test for beyond "Can you cram for a test given a copy of the test?" Is that what you're testing for?