During the school year, yy DS8 does Singapore math at school, and Dreambox at home. His teacher likes the TenMarks program- DS thinks it's boring, but I like the straightforward math. It's a good "check" for understanding.
When I want to introduce new ideas, I use "Horrible Maths" and a book called "Help your kids with math" by DK. It's actually quite a good book for introducing beginner algebra, geometry, etc. or topics that tend to interest gifted math students (golden ration, etc.)
We tried Beast Academy and may work with it a bit this summer. I think DS needs to develop more patience for it because the problems are more analytical and time consuming. He is likely moderately ADHD, and loses his cool easily.
All that said, I think Singapore math is a solid elementary school curriculum with the potential for high level thinking via challenging word problems.
Because DS goes to private school, I am introducing algebra gradually into his thinking, rather than looking for a formal algebra curriculum. It shocks me that in a couple of years, DS may be ready for "real" algebra.
