High school science: Which courses are "rigorous"?

I received an interesting call today from a high school science teacher in a state that has increased its graduation requirements in science in recent years. The state board in this state has set about determining which science courses meet the criteria of "rigorous" for purposes of fulfilling unit requirements in this subject--and this teacher was surprised and dismayed that some subjects she teaches--including AP Environmental Science--did not make the cut.

Her concerns did raise the question of how states striving to ensure rigor in high school graduation requirements in science determine which courses are "rigorous". Of course, there is the heavily-cited research identifying a correlation between high school coursetaking in lab-based biology, chemistry and physics and subsequent entry into and completion of a baccalaureate degree within a reasonable period of time. Yet not all courses approved by such states as "rigorous" seem to fit into the categories identified in the research, while others explicitly intended to bring students to college readiness--such as AP science courses--are not wholesale included in the definition of "rigor" in every state.

Transparency by state-level entities regarding the process used to define rigor among high school courses may result in greater buy-in from teachers, students and parents that the path to greater rigor in high school graduation requirements--in science as well as in other subject areas--is the right path to tread.