The Impact of Using Coherent Curriculum on Students’ Understanding of Core Ideas in Chemistry

~1,225 middle school students, 6 schools in 4 US states, 3 grade levels, 2 school years

US middle school chemistry (matter and its interactions), IQWST coherent materials vs traditional district materials.

Non-randomized comparison: schools/classes using the IQWST coherent chemistry sequence vs schools using traditional materials, analysed with IRT scaling plus HLM. Assignment was by school, not random, so selection into the coherent-curriculum condition is uncontrolled — the schools that adopt IQWST differ from those that do not, and the paper cannot separate curriculum coherence from adoption motivation, PD intensity or teacher quality. Joseph Krajcik is an IQWST co-PI, so this is the developer's own evaluation of the developer's own product: developer-involved at minimum. The outcome is a researcher-developed, IRT-scaled assessment of chemistry core ideas built by the same research programme, i.e. curriculum-aligned. No independent standardized measure is reported. Print issue: International Journal of Science and Mathematics Education 17:295-315; Crossref online date 2017-10-25.

This is the closest thing that exists to a controlled test of curricular coherence in science, and it is a non-randomized, developer-involved comparison on a curriculum-aligned measure. The coherent curriculum shows a 'promising' effect on students' understanding of chemistry core ideas, concentrated in high- and middle-performing schools, with limited benefit in low-performing schools — the same efficacy-to-effectiveness pattern this archive sees everywhere. No effect size is stated in the abstract. Note what the design does and does not isolate: the treatment is an entire curriculum package (materials, activities, PD, storyline), so any effect is attributable to the package, NOT to sequencing or coherence per se. Nothing here identifies the causal contribution of the ORDER in which the content was taught.

Medium-high. Schools self-selected into the coherent-curriculum condition; students within them are not comparable by design, and prior-achievement moderation (works in high-performing schools, not low-) is exactly the pattern selection produces.

No RCT of IQWST exists. Its predecessor curriculum (LeTUS) was reviewed by the What Works Clearinghouse (ED531792, 2012): five studies screened, none met WWC evidence standards. A separate developer-run randomized study of the AAAS 'Toward High School Biology' coherent unit (Herrmann-Abell, Koppal & Roseman 2016) found positive effects on a developer-written posttest with 6 teachers and ~600 students.