My schedule changes every 2-4 weeks. Students are added, moved around, or no longer need my help. It's easy to just copy and paste kids around in your schedule but I really recommend printing out a new copy of your schedule EVERYTIME it changes. Keep them all in a folder with the dates of the changes and why it changed. I would also keep a list of students in that folder. When you get new students, write down their name and the date they were added. If students are switched from another teacher to you, have them email it to you. You can simply say "I have to go get my next group, can you just email me the name?" Get everything in writing...it's better to be safe than sorry.