Brief Description

DLDT is an observation tool used by teachers and includes 6 scales: two for receptive and expressive oral language, two for written language (reading and writing), and two for mathematics. Each scale consists of 9 behaviors or characteristics that may indicate learning difficulties. The tool was developed for use by both general and special education teachers, targeting students in the upper grades of primary school and early grades of secondary school, with the aim of early identification of potential learning difficulties.

Purpose

The goal of DLDT is to enable the timely identification of students who may be facing learning difficulties before formal diagnostic procedures begin. It supports early intervention and helps allocate support resources appropriately.

Scoring Method

Teachers rate the presence of each behavior/characteristic using a 9-point Likert scale (1 = never to 9 = always). The mean score is calculated for each scale, as well as an overall mean score across the entire tool.

Validity

Different forms of validity were assessed, including construct, conceptual, discriminant, and convergent validity. Confirmatory factor analyses confirmed the tool’s structure, and discriminant validity showed high rates of differentiation between typical and atypical learners.

Reliability

Cronbach’s alpha coefficients for each scale are exceptionally high: 0.96 for receptive language, 0.97 for expressive language, 0.95 for reading, 0.97 for writing, and 0.95 for mathematics. Test–retest reliability also yielded coefficients above 0.95, confirming the tool’s high reliability.

Data Analysis and Use

Data analysis is conducted using mean scores per scale and overall. The results are used to identify high-risk students and inform decisions for intervention or further evaluation. The tool was implemented with a sample of 1,306 teachers across 319 schools in Greece, covering diverse regions and student population characteristics.

References

Algozzine, B., & Ysseldyke, J. (1986). The future of the LD field: Screening and diagnosis. Journal of Learning Disabilities, 19(7), 394–398.
Hamill, D. D., & Bryant, B. R. (1998). Learning Disabilities Diagnostic Inventory. Austin, TX: Pro-Ed.
Lyon, G. R., Shaywitz, S. E., & Shaywitz, B. A. (2003). A definition of dyslexia. Annals of Dyslexia, 53, 1–14.
Snowling, M. (2000). Dyslexia (2nd ed.). Oxford: Blackwell.