Foundational Reading Knowledge of Teachers of Students With IDD: Examining Experience, Degree and Time Use

Background Special education teachers require foundational reading content knowledge (e.g., phonemic awareness, phonics) to teach early reading skills. Though many measures have been developed to measure such knowledge, none have examined item‐level differences related to teacher characteristics (i.e., experience, degree and instructional time use). Method In this study, we examined the psychometric properties of the 20‐item Teacher Knowledge Assessment: Structure of Language scale using data from 337 special education teachers providing reading instruction to students with intellectual and developmental disabilities in the United States. Results Out of 20 possible total points for correctly answered items, the average score was 13.2 (SD = 3.5). We conducted Rasch analysis and dropped two misfitting items, resulting in 18 items on the scale (M = 11.9; SD = 3.3). Using dichotomous teachers' years of experience (≤ 5 years vs. > 5 years), education level (bachelor's or below vs. advanced) and self‐reported time teaching phonics and phonemic awareness (≤ 20% vs. > 20%) as focal variables, we conducted differential item functioning (DIF) analyses as part of the Rasch analysis. A greater number of items showed DIF for teacher experience or instructional time use (8 items each) than for degree (3 items), with easier and harder items identified for each subgroup. Conclusions These results evince inconsistencies in teachers' acquired foundational reading knowledge based on experience, degree and instructional time use. Structured literacy standards for teacher preparation programmes and in‐service training initiatives may provide the means to address gaps in teachers' knowledge.