What on hearth is going on?
Other the time you a teacher, must have created and share a wealth of presentations and content on the Internet. But are you really getting the recognition you deserve?
You will quite often that many sites take control of your content that you share and gladly upload it and share it with their visitors without giving you credit for it.
In your situation you develop a lifetime of material at home not getting paid for it, and share on specific websites. You are then face with the problem of your content is not only the school or college your work for content, but now some sites are claiming audience on back of your own hard labor.
The good thing is that if you work for a college that take copyrights seriously they will chase the thief and kindly ask them to take down your hard work from their. But the bad side is that if you are working freelance you then have to chase thief yourself and take action, but it is not easy.
I will make my own website and drive traffic to it by getting the whole world content free to download. Clever business.