When kids in DS8's class test out of spelling, they keep going until they score less than 90%. DS8 is in 6th grade spelling book, but a kid in his class is in the 8th grade spelling book. I asked for them to use Caesar's English for word roots and vocabular development next year. There are 2 levels of Caesar's and then Word Within a Word, so there's plenty to do there.
In that class, kids work on math concepts as a class (recently perimeter, circumference, area, volume) once a week. The other days they work independently on ALEKS (2 days) and Accelerated Math (2 days). That way they can progress at their own rate and keep learning new concepts. I agree with LMom that you should talk to the teacher, perhaps equipped with some tools that can be used (Caesars, ALEKS, AM).