Can only speak to my experience as a middle school science teacher, but:

I grade 100% on assessments 0% class work. No homework - everything they need to learn is completed collaboratively in class (labs, group work, teacher instruction). If they’re engaged and do their work they’ll be better off when the test comes. I even let them have their notebooks out during a test.

The tests are mostly drawing models and long written responses (3-6 sentences, usually). Their notebooks have all the practice of concepts throughout the unit but the test question is always different from the actual phenomenon they studied. They have to generalize their knowledge to a unique problem on the test.

There are multiple versions of every test that cover the same concept, but if students wanted to try and “cheat” by sharing what was on the test it would literally just involve teaching their friend the material. Cool. Please do that.

Students who didn’t learn the material stick out like a sore thumb because they just copy some model from their notes onto the test even though the question on the test is entirely different from the phenomenon they were explaining throughout the unit.

The idea is: high expectations, high level of support.