(a) An assignment for Environmental Systems, Advanced Placement (AP) Environmental Science, International Baccalaureate (IB) Environmental Systems, or Aquatic Science, Grades 9-12, is allowed with one of the following certificates.(1) Chemistry: Grades 7-12.(2) Chemistry: Grades 8-12.(3) Grades 6-12 or Grades 9-12--Biology.(4) Grades 6-12 or Grades 9-12--Earth Science.(5) Grades 6-12 or Grades 9-12--Science.(6) Grades 6-12 or Grades 9-12--Science, Composite.(7) Junior High School (Grades 9-10 only) or High School--Biology.(8) Junior High School (Grades 9-10 only) or High School--Earth Science.(9) Junior High School (Grades 9-10 only) or High School--Science.(10) Junior High School (Grades 9-10 only) or High School--Science, Composite.(11) Life Science: Grades 7-12 or Grades 8-12.(12) Legacy Master Science Teacher (Grades 8-12).(13) Science: Grades 7-12.(14) Science: Grades 8-12.(15) Secondary Biology (Grades 6-12).(16) Secondary Earth Science (Grades 6-12).(17) Secondary Science (Grades 6-12).(18) Secondary Science, Composite (Grades 6-12).(b) An assignment for Environmental Systems, AP Environmental Science, or IB Environmental Systems, Grades 9-12, is allowed with a valid secondary or all-level teacher certificate plus 24 semester credit hours in science, including at least 12 semester credit hours in environmental science and/or ecology if assigned prior to the 1989-1990 school year or any science teaching certificate with 12 semester credit hours in environmental science and/or ecology.