I had one of these when I was little and remembered being amused by it for great patches of time! This one lights up when attached to the frame, which is an added interest, and is not so difficult to master that children cannot do it but difficult enough for them not to become bored too quickly. Not overly educational but gives a hand on experience of forces in the way the child has to move their hand to get/keep the wheel spinning
Note: when I first took it out of the packaging I thought it was faulty as I could not get the wheel to spin all the way around. However, by moving the plastic strip on the handle up or down, you can change how close the bars are together and this affects how the wheel spins.