Just as a note about difficulty it's quite hard for me to try to get this at a good curve, I have tried to make it so that all the levels have more than one way to complete the objective,
Level 3 has 4 ways of doing this angle 172 power 240-255 and just time it so the moving plat is just starting to move the other way and the spinner is vertical and EVERYTIME you get the ball in 10/10, But the other way is power around 40-50 and bounce the ball off your ledge into the rotating spinners and it should drop in nicely depending on timing of moving platform, not 100% guarantee though, another way is to have power around 90 and aim at the 2nd spinner as is comes round just before its vertical and it riqochets (dam spelling) nicely in. Or at around 48 power you can if timed correctly just shoot the ball in, in an arc sort of fashion, i call this the beckham shot (hehehe).
You will find that ALL the levels have EASY ways to accomplish the task.
But i'd like to hear what Order you think the levels would be best to go in from easiest to hard.
Just a note on how i design the levels, i put the firing point in and the exit point, and try firing the ball in, then i put obsticles in the way, some help and some hinder, i then test that i can do this and take it from there.