Interesting thoughts from so many people.
Having worked in software for most of my working years,
I've had a bit of exposure to IP concepts and laws.
There are currently many debates going on in the world about
similar concepts and 'the jury is out' on most of them in my opinion.
The Tasmania example is interesting to note, I agree. It must be remembered
that a lawyer wrote that for the institution. If it were written by the
creative contributor, it would have been written from an opposite viewpoint.
The world's creative property is generally controlled by greed, power and manipulation.
Look at the music industry. Also, look at the Movie industry.
Why do I mention this? Power, greed, legal tricks, lawyers and manipulation are the norm and are how things are done in general. I wouldn't use ANY of them as any more than background information when it comes to making a moral/ethical decision.
The truly key factor here is how you feel. This product is something you created.
You own what you create forever in the most basic terms. No one can copy you - not yet anyway. So, you are obviously the most valuable part of the equation and that is safe.
When it comes to China's regard for copyright and IP as well as fair compensation or desiring to see a foreigner do well... we know how that goes 99% of the time.
It seems you want some recognition. I was teaching in Thailand a few years ago and I
used to get the class yelling (inspired in part by Li Yang's work). After a few weeks, all the English teachers were using that technique in their classes. I was flattered and happy that they took my idea and it benefited them. I would never recommend holding back something that will truly benefit others based upon your own vanity. I would have liked to have heard 'hey, we're using your idea and its working'. Oh well.
I was teaching in Beijing several years ago in the 'Business English' circuit when I heard about some American guy that had some cool technique for teaching business English. He wouldn't share it with me nor would one of his teachers. He quit teaching He left China. So did his idea. Now no one can benefit. My point is this; being too greedy doesn't give you a chance to help others.
There is a more creative approach. You've created some Ppt lessons that you are obviously proud of and value. You should package them in a way that you can sell them. You're a teacher by trade. I'm not asking you to bake me a cake as a gift here. Someone has walked into your bakery and asked for your recipe and one of your cakes for nothing in return. A creative and fair answer may be: If you like my cake, I'll make a special package for you. (sorry for the sloppy example) In my opinion, this is not a legal question or one of manners. It is a challenge to you to effectively and ethically take advantage of the value you bring to this earth.
Now I'm curious about your lessons...