Our district:

Below average:
6th: 6th grade math
7th: 7th grade math
8th: 8th grade math
9th: Prealgebra or Algebra I

Average:
6th: 6th grade math
7th: 7th grade math
8th: 8th grade math or Algebra I
9th: Geometry or Algebra I

Highest:
6th: Prealgebra
7th: Algebra I
8th: Honors Geometry
9th: Honors Algebra II

Students with higher levels of achievement are sometimes placed at a higher level. For example, I know of a 6th grade boy who was placed in Honors Geometry (upon entry from homeschooling). But these placements are rare, especially among kids who have been in the system since K.