I think it depends on what your goals are and whether or not you are willing to completely rethink math. I had a similar experience to MrsB. Two of my kids worked through Fractions and Decimals after doing other curricula for their previous years. They had a lot of trouble with the books and a lot of frustration.
We were at the point of dropping Fred completely. But I was so convinced that his methods are sound and that self-teaching is the best way to learn. I decided to try one more book. We got the Elementary Physics book and I worked through that with them. This is NOT what the author recommends. But I knew that my kids needed to learn how to learn that way. Every single day they read the chapter on their own, then did the problems, then we discussed so that I could make sure they were understanding. This necessitated me also working through the book so that I could guide them as needed. More than once, we had to back up and re-learn lessons. They each started keeping a small math notebook where they could write down formulas, rules, etc. that they would need to know in future. Let me tell you, that book is hard. After that I decided we would switch to Teaching Textbooks or something. By this time, however, my kids wanted to keep on trying with Fred. So they worked through Pre-Algebra with Biology and now are almost done with Pre-Algebra with Economics. I am happy to say that they are both doing great now. There are no more tears and frustration. So far. They have done these two books entirely on their own.
I think they had to figure out for themselves that you MUST learn the lesson before moving on. If you move on without understanding, you are going to be lost a few lessons down the road. A couple of weeks ago, my 8th grader said that math was actually becoming enjoyable now that she understands it.
Meanwhile, my younger 3 are working through the elementary series. My almost 6th grader my almost 4th grader will finish working through the series in the next year and then we will move on to Fractions. Because they have been working through the whole series, I really don’t anticipate any problems as they move into the higher books. They know the teaching style and they are getting such a GREAT introduction to the higher maths. My soon to be second grader is about halfway through Farming. I am amazed almost daily at how these younger kids actually think mathematically. I feel very good about the instruction they’re receiving from LOF. My youngest has done nothing except LOF preceded by the first two Miquon books and I am so impressed with his math thinking skills. (I’m not bragging on him, but on Fred. I think it’s all due to what he’s learned in LOF.)
I have decided that when the older two finish this last pre-algebra book, I want them to quickly read through the elementary series before moving on. As I read through the books with my younger ones, I am so impressed with the way Stan Schmidt teaches them these really abstract and difficult concepts in a way that even my 6 year old understands. I want that for my older kids as well. I think it is worth taking the time to go through them before they start algebra.
My oldest daughter, who is now in college, was my guinea pig. We tried lots of different maths. I completely agree with MrsB that skipping around is so bad. I do think that just about any math curriculum will work for anyone if you are consistent with it. That said, LOF is the best I’ve ever seen. It accomplishes my goals – that my kids like math, that they see beauty in it, that they understand what they are doing, and that they realize that math is more than just a school subject they have to get through.
For what it’s worth, I do have one friend who is just a little ahead of us in LOF and her son has been using it exclusively since Fractions and they are having success also. I think there is a learning curve that you have to work through. It was almost a paradigm shift for us.