We haven't taken this approach, but that's a good sign, as we messed up big time. Our son actually completed 4th grade Math at one school and started 8th grade math an another school, but because he was doing it 'in school' and on the schools timetable, and at the expense of history class, it was a 3 month experiment that failed.

OTOH, he is now in 7th grade doing the same '8th grade' pre-Algebra class and it's going well. I think that if we had do what you propose it would have been 'just fine.'

I wish that there were Math books that cover 5-8 in a non repetitive way, and maybe there are. Your plan sounds flexible and totally reasonable. What have you got to lose? Nothing really.

BTW - I really like the book "algebra to go" - a suggestion from Hoagiesgifted.org

Smiles,
Grinity

Coaching available, at SchoolSuccessSolutions.com