I love AoPS, so apologies for lengthy response. VR00, AoPS has a number of components which you can put together as best suits you:
* Textbooks for each course, plus solutions manuals
* Alcumus, a responsive on-line database of problems connected to the topics in most of the Intro-level courses (free)
* Videos for all the major topics in pre-Algebra and Algebra (free)
* On-line courses, usually 3-6 months long, with a weekly class and a specific schedule.
We've tried a bit of all of them. After grade 4, DS10 and I did a high-speed run through the whole Pre-Algebra book, focusing on learning just enough to do the problems on Alcumus and prep for the Algebra I on-line class in October. About half-way through Algebra we had to concede it was going too fast for us to keep up with as only after-schooling. So we stopped the class and have reverted back to using an AoPS text at our own pace again.
Texts: I love the books for all the reasons described above: this is what “Discovery Math” should be. Very little repetition: every question has a new twist to figure out. And a quirky sense of humour. As noted, Pre-Algebra is not “too hard” in the sense that it assumes nothing: it starts at 1+1 and seems to cover everything a kid might learn up to middle school (useful for us, since DS hadn't really been taught much of anything yet). But it jumps quickly into complex uses of the ideas, so you get the basics without getting stuck in them. I make extensive use of the solutions guide for Algebra (to my combined delight and dismay). AoPS presents and encourages multiple approaches, so I often check to see if there was an interesting or easier way to get there.
Alcumus and videos: Alcumus provides practice problems and some added incentive, even for my deeply non-competitive kid. The videos are well-done, and enjoyable to watch, though DS didn't have the patience to watch many of them in pre-Algebra (we should try again in Algebra). With just the free stuff - videos + Alcumus - you can get a good overview of the material, but may only scratch the surface compared to tackling the challenge questions in the textbooks. If we'd done pre-Algebra properly (and not just the Alcumus version), we probably could have kept up with the Algebra class, but our knowledge was too shallow and rapidly obtained.
On-line classes use all of the above resources. Students are expected to read a chapter before class, and do as many of the problems as possible/ needed afterwards. With so little repetition, skipping problems generally means missing the chance to tangle with a new concept. The weekly class time really just reviews the new chapter and works through some basic problems, but the class itself is surprisingly interactive. DS would respond to hundreds of queries - from the micro "any questions?” to complex solutions - over the course of the hour and a half. DS is an OK typist but not a fast responder. In early classes, I was unprepared for how demotivating it was that his responses were always submitted too slowly to be among the ones posted. This was almost a deal breaker for the first couple of classes. However, as the material and questions got harder, solving the problem mattered more than speed of typing the answer, and DS could often get "on the board" - and loved doing so. My DS does have writing issues, though, so for both class and text work I scribe on a whiteboard for him, so he can concentrate on content and typing in his responses.
Multiple TAs monitor every response during class, and offer individual help if a student looks like they are struggling. The class also has its own discussion forum where both teacher and students share questions and ideas, anytime. “Marked” homework includes all the Alcumus problems associated with the chapter, plus a weekly set of about 10 challenge questions. Most are answered with a single response on-line, the same as Alcumus. One will require extensive written proof/ explanation of how an answer was developed, and will get fairly extensive and useful written feedback.
