An investigation of the impact of science course sequencing on student performance in high school science and math

Students in a single Texas school district that offered BOTH the traditional biology-chemistry-physics sequence and the physics-first sequence; exact student counts not verified (dissertation full text not obtained).

US high school students, grades 9-12, in one Texas district; outcomes are Texas state end-of-course exams in biology, chemistry, physics, Algebra I and Geometry.

Doctoral dissertation, University of Texas at San Antonio, 2015 (ProQuest 3721730; ADS bibcode 2015PhDT.......166M). The identification is the useful feature: ONE district ran both sequences concurrently, so district effects, state standards and the outcome instrument are held constant while the ORDER of the three sciences varies — the closest thing in the literature to a natural experiment on high school science course order. It is still a quasi-experiment: students were not randomly assigned to sequence, and within a district that offers both, selection into physics-first is plausibly by prior maths attainment, campus and counsellor advice. The outcome is a genuinely INDEPENDENT standardized measure (Texas EOC exams), not a researcher-designed test, which is rare in this literature and is what makes the null informative. Read depth is secondary: the abstract and its published summaries were obtained, the full dissertation was not, so no effect sizes, sample sizes, covariate set or attrition figures are recorded here. That is real debt on this archive's single most load-bearing null.

This is the headline finding of the whole sequencing topic and it is a NULL. The sequence in which students took biology, chemistry and physics had 'little or no impact' on performance on the end-of-course assessments in each of those courses, and only a minimal effect on mathematics performance (Algebra I, Geometry). The conclusion stated is that neither the traditional nor the physics-first sequence presents an advantage for student achievement in maths or science. Weight this correctly: it is a single unreplicated dissertation in one district with no reported effect sizes, on a standardized outcome, so it does not by itself establish that order is irrelevant — it establishes that the one study that looked for an order effect on an independent measure did not find one. Combined with the total absence of any randomized or IV evidence on science course order, it is the best direct evidence the question has.

MEDIUM. Not randomized, so students who took physics first differ from those who did not; but the direction of that bias would normally INFLATE a sequence effect (physics-first students in a district offering both are typically the stronger maths students), and the study found none. A null that survives a selection bias pointing the other way is more credible than a positive would be.

Unreplicated. The only other physics-first evaluation located is O'Brien & Thompson (2009, The Physics Teacher 47(4):234-239, DOI 10.1119/1.3098211), a matched comparison of 9th- vs 12th-grade physics classes in Maine using FCI-type conceptual instruments, whose own abstract states that 'there is no actual evidence to assess the success, or failure, of this substantial shift in the science teaching sequence' and which found 9th graders more sensitive to instructional method rather than uniformly worse. Larkin (2016, School Science and Mathematics 10.1111/ssm.12168) is a qualitative three-district case study of physics-first reorganisation that ends by calling for effectiveness studies; it reports that coordinating 9th-grade physics with 9th-grade algebra was harder than expected everywhere, and that biology enrolment dropped sharply for 1-2 years during each transition. No randomized, IV, RD or difference-in-differences study of science course ORDER exists.