How well do schoolchildren and adolescents know the form and meaning of different derivational suffixes? Evidence from a cross-sectional study

As children advance through school, derived words become increasingly common in their reading materials. Previous studies have shown that children’s knowledge of derivational morphology develops relatively slowly, but there is more to learn about this development. This study examined differences in knowledge of the form and meaning of suffixes across grade levels (Grades 3, 5, and 8) and different types of derivational suffixes (adjectives and nominals). We assessed 309 English-speaking children on word reading and receptive vocabulary tests and two tasks designed to assess the form (orthographic knowledge) and meaning (semantic knowledge) of 28 derivational suffixes (14 adjectives and 14 nominals). Overall, our findings showed a significant improvement in identifying and understanding derivational suffixes from Grade 3 to Grade 5 and a smaller, but still significant, improvement from Grade 5 to Grade 8. Our findings regarding suffix types were mixed. While written forms of adjectives were identified more accurately than nominals across all grades, this advantage did not extend to the students’ understanding of the meaning of the suffixes. These results highlight the distinction between the identification of suffixes and the understanding of their meaning. We discuss our results in relation to suffix frequency in children’s reading materials.