Singapore Math (SM) and Rightstart (RS) are very similar in methodology. However the scope and sequences are different. SM is more pick up and go, jump ahead, jump back, easy to compact and to accelerate. RS on the other hand is very difficult to compact or accelerate. I love RS. I've done levels A and B w/ my boys. I love how topics are interweaved and it helps the kids to make the leaps on their own to the next level. But that is what makes it difficult to compact. The warm-ups are setting up DC for some concept 10 lessons down the road so if you just skip to that lesson, you miss the preparation. For ex: in the geometry lessons you finish up by making equilateral triangles and folding them into thirds and fourths. Then you fold them into thirds and then the same one into fourths and vice versa. I thought "hhm this is laying the ground work for LCD and adding unlike fractions in the next level." RS is more of a committment than SM. I felt like I couldn't teach SM the way it's meant to be taught since I didn't learn math that way. Now that I've taught RS, I could teach SM easily. I love SM Challenging WOrd Problems (CWP) which is a good supplement to any math program. I also like Zaccaro's books - those are supplements and not stand alone curricula.
You can view sample pages of RS at
www.alabacus.com. If the price scares you, you can buy it used very often as well as buy gently used copies from RS (ones that were out at convention so have ONE page with a crease lol).
hth
