From blog.ciaraballintyne.com
In many contracts schools state that they own the rights to any and all material you create while working with them. Is it legal? It depends on the country you're in and what you're using it for. Some countries are well-known for breaking copyright laws left and right and intellectual property laws can be a mess.Now let's suppose that you decide to re-use material you created while working at a past job, just how could your ex-employer know about it? Chances are pretty slim that they'd find out, after all, someone would have to tell them about it.
What if they did find out? How could they prove that you created that item while under contract with them? If they collected your materials (and didn't throw them away) that would be one way. However, you could always claim that you created it while at another past job and not while working for them.
What happens if they can prove that you made something while under contract with them, that they own the rights, and you're breaking country? Well, they might take you to court over it. Chances are this would only happen if you were trying to make a profit off it, by selling it or publishing it. Using it in another class probably won't get you into trouble, after all, there are laws that protect teachers and allow them to use copyrighted material for educational use. Hopefully you'd be able to get out of it by apologising or in the worse case fleeing the country. If you're clearly in the wrong, then you had better lawyer up and pay the consequences.
To make sure that you don't get taken to court, find out if schools can legally own the material you create while working for them. And if they do have the right to it, and you want to re-use it in the future, make sure that you keep all your material (don't give anything to students, teachers, or admin) to yourself. Better yet, to make sure you're not breaking the laws, if you want to re-use material in the future, change it a little bit and make it different than the material you created while working for them.
