I can see two approaches for a class of 50 students. I am using a trite example, not really suitable for a college class, but I think it makes the point:
In-class exam: all 50 students sit in a room with a piece of paper and try to write down the names of the 50 states. If you have memorized the necessary facts, this in-class test is not hard.
Take home exam: since you can use reference books, or even work in groups, we need to do it differently. Each student is assigned a different state. Each student must crunch the economic statistics for their state covering the last 20 years and compare growth in state tax revenue against demographic shifts between urban and suburban enclaves.
What’s that? The take home exam is really, really hard? But, hey, you get to use Google and stuff, right? And you can work in groups — so the guy who has Hawaii and help the girl who has Texas. Except the states are totally different, so helping each other isn’t much of an option.
Well, if they fail their take home test, maybe they will learn a lesson and sit quietly for the next in-class test.
One class I had did something interesting. The exam was to write two essays in two hours. The trick was that there were eight possible questions which would be posted a day or two before the exam, of which two would be selected. You could write all eight essays before the exam, find out which two were picked and turn those in. You could just go in cold. Most outlined all eight, picked their major references, dug up appropriate quotes and finished two in the exam.
“try to write down the names of the 50 states”
Bar bet: List the 50 States (abbreviations OK) in 5 minutes. Try it. Not one out of 100 can do it.
Fun with the grandkids: Write down 12 body parts that are spelled with three letters. Five minutes. Get started with “EAR.” Some kids get inventive. Be prepared to interpret the rules.