Why do schools refuse to send exams home?

http://www.washingtonpost.com/blogs/class-struggle/post/why-do-schools-refuse-to-send-exams-home/2013/07/21/ad6818a2-f0dc-11e2-a1f9-ea873b7e0424_blog.html

Oh, this brings up little miserable memories for me. While I let students keep every piece of homework they did, and they got their daily quizzes back, I had decided that I would keep tests because I wanted to reuse them. I'd seen a number of students cheating with copies of old tests from older students and didn't want that happening to me, so I kept the tests. Sure, I would show them to parents (and made copies for them upon request), but otherwise they were carefully organized in my files. At the end of the year, before finals, each student would spend several days reviewing all their old tests, and it was nice to see them reflect on the progress they'd made through the year. Still, some parents didn't like my policy, and some students took advantage of it to tell their parents that they "couldn't study" because I kept "everything." I'd probably do things a little differently now, of course, but I'm still very well aware of the effort it takes to make good tests every year.