The Effects of Morphological Instruction on Literacy Skills

22 studies (Review of Educational Research 80(2), 144-179)

Preschool to Grade 8 (roughly ages 4-14)

Systematic review with meta-analytic averaging of Cohen's d by linguistic outcome category (morphological sublexical, non-morphological sublexical, lexical, supralexical) and by comparison group (experimental vs control, experimental vs alternative training). The comparison against ALTERNATIVE TRAINING rather than only against no treatment is what makes it usable - it distinguishes "morphology works" from "instruction works". Recorded in the spelling topic because English spelling is morphophonemic, so morphology is where spelling instruction goes after the phoneme-grapheme layer is secure.

Morphological instruction benefits learners; it brings particular benefits for LESS ABLE readers; and it is no less effective for YOUNGER students than for older ones - which contradicts the common assumption that morphology should wait until after the code is mastered. Effects were larger when morphological instruction was combined with instruction in other literacy skills than when delivered in isolation, which is the same "embed it, do not run it as a separate unit" pattern the archive records for comprehension strategies and for grammar.

Low for direction (intervention studies with control or alternative-training comparisons). The "particular benefit for less able readers" is a subgroup contrast within intervention studies and is partly regression to the mean.