We just finished 5A of Singapore Primary Mathematics. We also do a mental math practice book from Sinagpore and Hands on Equations and some of the Process Skill book 4. I decided to print out the Math Mammoth tests and try those as well. I find the curriculum to be so different. Like the chapter test 1 had exponents ... we haven't learned those yet (and I actually don't see them in Singapore book 5B either). The Math Mammoth test also had lots of variables and prime factorization - again, two things we haven't see.
So, it makes me wonder if I need to add these things in to Singapore or if these are concepts that MM introduces early. Otherwise, I am very happy with Singapore.
Thanks for any help!