The Development and Psychometric Properties of the Handwriting Assessment Tool for Primary School Students

This study aimed to develop the <i>Handwriting Assessment Tool for Primary School Students</i> as a Thai handwriting assessment and evaluate its psychometric properties. Participants were 25 primary school students in Grades 1-3, four classroom teachers, and one school-based occupational therapist. The study comprised two phases: (1) developing the tool, and (2) investigating its psychometric properties, including content validity, internal consistency, inter-rater agreement, and stability reliability. The final tool consisted of two parts: general information on students and writing-related factors, and handwriting performance across five domains including alphabet and numerical writing, copying, dictation, legibility, and writing speed. Results indicated acceptable content validity (IOC = 0.80-1.00), excellent internal consistency (<i>α</i> = 0.96), acceptable inter-rater agreement (IRA = 92.22%), and excellent stability reliability (ICC = 0.97). The <i>Handwriting Assessment Tool</i> appears to be a valid and reliable instrument for evaluating handwriting performance. Further studies with larger samples are recommended to enhance generalizability.