Educational Impact and Implications StatementWords can consist of several meaningful parts, or morphemes, such as -ist in guitarist and re-in reuse. Understanding common morphemes helps children infer the meanings of new words. In this study, we tested the effects of working with an educational application (app) focusing on morphemes. Children completed app exercises such as sorting words or pictures according to their meaning, combining morphemes to build words, or identifying the correct word or morpheme to fit a sentence or picture context. We found that the app was effective in improving Norwegian second graders' ability to explain, understand, read, and spell words, including words which were not shown in the app, but which contained trained morphemes. The brief low-cost training produced long-term effects with a minimal burden on teachers.

This study aimed to determine the dimensionality of morphological knowledge by examining different sources of variance. According to the Morphological Pathways Framework (Levesque et al., Journal of Research in Reading, 44, 10-26, 2021), morphological awareness, morphological analysis and morphological decoding are related, but distinct dimensions of morphological knowledge. However, multidimensionality might also stem from construct-irrelevant variance due to methodological artifacts. We assessed 612 Norwegian third graders on five measures of morphological knowledge and one measure of general vocabulary. Fitting a series of confirmatory factor analysis (CFA) models, we evaluated the dimensionality of morphological knowledge both within and across the five tests. Furthermore, we fitted three structural equation models (SEMs) to explore how different conceptualizations affect the relationship between morphological knowledge and general vocabulary: a five-factor model, a bifactor model, and a higher-order model representing morphological awareness, morphological analysis and morphological decoding. CFAs supported a multidimensional view of morphological knowledge and highlighted the need to account for construct-irrelevant variance. SEM analyses further illustrated that construct-irrelevant variance introduces a confounding element to the relations between morphological knowledge and vocabulary in the test-specific five-factor model, as only the bifactor and higher-order models separate between construct-relevant variance and variance due to methodological artifacts. The bifactor model is useful for separating sources of variance, especially during test development. For research purposes, however, we recommend conceptualizing morphological knowledge in line with Levesque et al., Journal of Research in Reading, 44, 10-26, 2021, to increase knowledge of morphological dimensions and their relations to other areas of literacy.

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