We have done pre-algebra and are now in the middle of algebra but have noticed a handful of instances when a problem is given before the lecture that explains how to do it--sometimes even right before.
Are you actually talking about cases where the question can't be understood until you know the meaning of some technical term in the question? I'd agree, then, that that's a problem; but the way this is worded makes it sound as though you think it would be ideal for a child never to see a problem they haven't yet been shown the techniques to solve. If what's what you meant, I (with my mathematician hat on, as well as with my parent-of-9yo-who-does-online-math hat on) really couldn't disagree more strongly.
IMNSHO, it's absolutely essential to see problems, make a serious attempt to solve them, and find that you can't, before you get introduced to a new technique. (At least regularly, if not every time.) Otherwise (a) you learn that you should be able to solve all problems, and that if you can't it means you haven't paid attention - which is false and damaging in the rest of life (b) why would you be interested in the new technique, for which you've never yet seen a need?
DS9 has done ALEKS courses on and off since he was 5; they have no teaching material, just questions. (They do have clickable definitions for new terms, which are useful, and worked solutions for the problems, which are not so useful.) DS prefers to call me if he gets stuck, rather than read the worked solution, so I have a fairly good idea of how often this happens, and it's rarely. Usually, he can work out how to tackle a question provided he can find out what the words in the question mean, because it's only a small jump beyond something he already knows how to do. He's two-thirds of the way through his current course and I suppose I've needed to explain something to him perhaps four times so far.
The AoPS books start each chapter with a few definitions, and then immediately some problems which you're supposed to work on before you read on. Then they work through the problems in the book, and often point out e.g. where a solution gets stuck for want of a result the reader doesn't know yet, or where a solution technique can be generalised and is worth writing down as a rule.
Of course children and courses are going to differ, and of course online courses (like books) will have bugs, but this pushed my buttons! Sorry if I've gone off on a rant against an interpretation that wasn't what you meant anyway :-)
