Background and Aim: There is a relation between language skills and science learning in educational approach. Hearing-impairment and delay in learning of language skills influence the progress of learning. The aim of this research was to study the effect of educational level elevation on growth of mathematical skill. Therefore, third grade hearing-impaired students of secondary school, and forth grade hearing-impaired and normal-hearing students of elementary school were compared in terms of mathematical skill.
Methods: The research was cross-sectional and the internationally standardized mathematics questions (2007) were selected as the tools of the test. The sample included 31 students of 4^th grade elementary and third grade of secondary school with sever hearing loss from exceptional schools, and 17 normal-hearing students were randomly selected from ordinary schools next to the exceptional schools in Robatkarim, Karaj, and Shahriyar cities, Iran.
Results: According to data analysis there was a meaningful difference between hearing-impaired students of forth and third grades and normal-hearing students in the three fields of knowledge, application and argument (p<0.05). There was a significant difference between the two hearing-impaired groups in knowledge (p<0.05), but they had no meaningful differences in the fields of application and argument (p>0.05).
Conclusion: No significant improvement was seen in the mathematical skill of hearing-impaired students by educational level elevation. Writing mathematical books for the pre-elementary courses, revision of teaching methods, and increasing teaching hours are necessary in mathematics.