It’s a question that intrigues me – I keep coming back to it in different ways. Not least because I describe myself to my students as more of a developer: I make things work – than a designer: I don’t make them pretty.
The one criterion I would focus on – rather than curriculum content (that’s another story) or aesthetics and presentation – is engagement.
Does it grip their imagination? Do they want to explore it more and work out new strategies? Do they want to apply principles learned to other concepts?
A tall order, I know – but it should give some food for thought…