PreK--2nd grade: ACE private school
3rd grade: Upheaval in family. We begin traveling with daddy. Didn't finish his Paces for 3rd grade.
4th grade: We begin Christian Liberty Press. They place him in 3rd grade Math. He finishes it.
5th grade: CLP still. He doesn't finish 4th grade book all the way.
6th grade: We begin HOD. It is determined (with Carrie's help) that we would have to go too far back to do Singapore. He finishes 4th grade CLP book and because I think he is struggling still with Math facts we did R&S 3. (bad idea, mad at myself)
I was raised doing Paces. I don't know how the Math schedule is supposed to go. I just did the Paces that were handed to me. I mistakenly thought that I had until he hit 11th grade to get him caught up and then he would do Algebra but reading the threads on this board I'm finding that's not true at all. I am starting to panic.

He is a very smart boy. It is not his fault that he's behind. Since he was little he's been fascinated with how things work and was able to put together elaborate Lego projects by himself. I think he could be an engineer or architect and I know that he will need lots of Math in order to succeed. I don't want to fail him.
Any advice on how to get him caught up would be appreciated. We found http://www.aleks.com this week and did the 3 hour free trial and he really responded well to that. The Geometry was his favorite part. Does anyone have experience with aleks.com? I am also willing to try the Singapore placement tests again this year to see if that would work. I mainly want to know how I can catch him up and have him done with all the courses he needs before graduating.