The aim of this study is to investigate the effectiveness of Gagne's model in teaching the concept of geometric shapes, triangle, circle and square, to a student with intellectual disability. A multiple-probe design across behaviors, a single-subject design, was used to demonstrate the effectiveness of the adopted model. The participant of this study was a 74-month-old boy with moderate intellectual disability. A criterion referenced form was used to measure the performance of the student. The results revealed the effectiveness of the model in teaching geometric shapes. Moreover, the participant's special education teacher and pre-school teacher both expressed positive opinions about the intervention process. The implications of this study can be used by teachers who are studying with students with intellectual disabilities in the planning and implementation of concept teaching.