Relationships between Area and Perimeter by Students with the Autism Spectrum Disorder. An Exploratory Study

Background: One of the difficulties that appear systematically in learning the geometric quantities area and perimeter is associated with the intuitive idea of the existence of a relationship of dependence between the two. This difficulty is common to students of different ages and has been analysed in contexts of typical development. Objective: To investigate what happens to students with autism spectrum disorder (ASD) when they are presented with activities involving the concept of perimeter and area. Design: A qualitative and exploratory methodology was used, specifically, a case study. A specific geometry test consisting of a semi-structured interview and an ad hoc test was designed and validated. Setting and Participants: The sample consisted of three students, two in fourth grade and one in sixth grade, all of them diagnosed with ASD and with an IQ above 80 points on the WISC-V scale. Data collection and analysis: The written productions and the semi-structured interviews were analysed and triangulated according to the categories of Avila and Garcia (2020). Results: All the children affirm that there is no dependency relationship between area and perimeter when area remains unchanged, but two describe a dependency relationship when perimeter remains constant. The requirement to exemplify their answers has helped them to realise their error. Conclusions: A guided intervention focused on the teacher's request to specify the answers through examples has helped to improve the understanding of these concepts and presents lines of future research associated with the creation of teaching practices for this type of students.