Math-U-See, but if your son likes to move on it might not be the best. (The entire Gamma book is about multiplication; at different levels and depths as it moves through, but multiplication nonetheless.) As far as hitting a concept and moving on, I'd also recommend Horizons. (Never having used it myself. LOL)
We use math u see as well (1st & 2nd grades). It's worked well & my daughter seems to need the review to keep it in her mind. It was what my best friend who homeschools 5 kids uses so I thought it should work for me!
We also use Math-U- See We love it, and both of the older ones are Using the Epsilon book at the moment.(grade 4 + 5) It was also recommended by our old neighbour in Oz (who is using it with her 4 children) I think that I have had more " lightbulb" moments than the kids. I wished I had such a great program, when I was learning maths (so many moons ago !!)
We use Saxon. I like how it prepares students for the presentation of new concepts gradually. By the time you get to the lesson that official teaches the concept, it isn't a huge leap in their understanding rather a small but decisive step. However, for a student who likes to learn quickly and likes to move on, I can see how Saxon would be frustrating as their is a constant review of past concepts.
I am mathmatically challenged, lol, so my dd and I just took our first pre-algebra lesson with math tutor dvd. I enjoyed it, and am looking forward to tomorrow's lesson.
Saxon - I like the way it reviews previous concepts over and over. I feel like that's a good way to cement the ideas in my kids' heads. My son's flying through the curriculum; he can easily do more than one lesson at a time.
I have Horizons 2nd grade and it seems to go a bit quick. It also repeats and learns something new. It's the spiral approach. Not good with the word lingo, anywho it's going well and if she don't get it I will stop and work on the problem areas. I have gotten the workbooks from the bookstore for extra practice.
I love this board I think we are going to give horizons a try this year. If it doesn't work well I think we'll try saxon next.
I think Horizons looks like a good choice. I am still trying to decide to between Horizons and Singapore for my son. My dd is getting MUS.