I was just putting finishing touches on our first big unit test that I am administering this year. It would be really nice if we could just use the same test year after year, but unfortunately board policy dictates that we must return tests for students to keep. Additionally since all teachers of the same course give the same assessments, the tests are typically taken and returned to at least 300 students for mosts courses. I work in a high-performing districts, and there are definitely some students I suspect would try and find previous tests from siblings or older friends. Given this, we need to change some things each year. I never completely start from scratch. Since it's math, I often just change numbers, but some problems are much harder to change (for example, this first test we have a really nice matching section with graphs that would be really hard to change). I would say by the end I generally change between 40-75% of any given test. What do you do? Just print the same test? Start from scratch? Somewhere in between like me? Maybe you work in district that lets you hang on to tests.