What does work for me #1 ~ Hidden Notebook Check

I teach high school and I don't require my students to use a specific type of notebook, I leave that up to them. I do, however, require that they do something that will keep them organized. After a full year (2 semesters) of math, they are required to take a Regents exam in order to graduate so it is very important they save all their work and stay organized. I have found that the students hate to get notebook checks, especially at the high school level, they think it is immature. Also, I feel like they need to learn how to start taking responsibility for keeping track of their own work without me having to go through their entire notebook. Something that I tried a few years ago that worked well and I still use all the time is a kind of hidden notebook check where I can make sure they have all their important work without them realizing that I am checking up on them. I set it up like a scavenger hunt game with a list of things they need to recover. I set a time limit, sometimes it is short (only a few minutes at the beginning of class) and sometimes it is a long period of time (like over winter break). The list also varies based on time allowed with only a few items on the list to a quite extensive list. Some of the things I put on the list could be as follows: the notes from a specified date, test #2, homework #15, the worksheet on solving equations, the formula sheet from coordinate geometry, etc. The students must find and hand in whatever they find (usually in a folder with their checklist) before the time is up. The more the students find and hand in, the more points they accumulate. These points are then used for a number of different things from points towards individual classwork grades to rewards such as an extra 5 points on the next exam, to entire class rewards such as a no homework night. The students seem to find it fun and they don't realize that I am making sure they save and organize their notes.