What math do you learn in grade 9?
It depends on what the school prefers. I would think that 9th graders in a school for kids with learning disabilities normally learn Pre-Algebra, or Algebra 1. For a 9th grade class in a mainstream school, I would think that most 9th graders would learn Algebra 1, Geometry, Algebra 2, or Trigonometry. I would think that Trigonometry is mostly for gifted 9th graders.