>>243
>Maybe cards querying the basic idea behind a solution to a DE could work?
I think this is a good idea. You should of course learn in whatever way suits you, rather than letting other people tell you how to learn, but in my opinion it is much more important to understand the general principle behind what you are doing with a certain technique. This gives you deeper insight into what is really going on, and is also easier to remember. You might forget the exact expression/method you want, but you can replicate it on demand so long as you can understand the idea, and you can also bring the same insight to bear on other equations.