My DD10 (entering 6th) is skipping pre-algebra, too. But she had to take Grade 7, 8 and Algebra readiness tests to show them her mastery of pre-algebra. Algebra 1 is HS credit course and they wanted evidence that the student complete regular 8th grade level Math before allowing Algebra 1.

I would guess that California or the school will have similar conditions prior to allowing the student to skip (especially to HS credit course).