I kind of disagree. I remember things much better when I screw up doing them. The fact that it isn't immediately evident what exactly is wrong with my query m

I kind of disagree. I remember things much better when I screw up doing them. The fact that it isn't immediately evident what exactly is wrong with my query means I have to go back and read, and figure it out. Much like debugging. I know your trouble isn't with the concepts, but I honestly think that the extra step of saying, 'why isn't this working' will make the concepts stick around much longer than they would otherwise.