Background: A substantial proportion of children with autism spectrum disorder (ASD) also have an intellectual disability (ID). However, the academic achievement levels of students with ASD and ID (ASD-ID) are poorly documented and known. Method: We systematically reviewed studies on school skills (reading, spelling, and math) in children and adolescents with ASD-ID. The search was conducted in seven bibliographic databases: Embase, Pubmed/MEDLINE, PsycINFO, Cochrane Library, Ebscohost, Proquest, and Scopus until 28 May 2022. Results: We identified 33,750 reports, four of which met the inclusion criteria for the review. The studies, characterized by Level III evidence (non-randomized controlled trials), included 535 students, 266 in the ASD-ID group and 269 in the ASD-no ID group. A random-effects model meta-analysis revealed that students with ASD-ID had significantly lower reading, spelling, and math scores than students with ASD-no ID. The effect sizes associated with reading score differences were large, although with significant heterogeneity; similarly, the effect sizes associated with spelling and math score differences were also large, although to a lesser extent than for reading. Conclusions: The co-presence of ASD and ID is associated with significant deficits in reading, spelling, and math. However, the present meta-analytic results rest on a limited number of studies. This contrasts with the substantial proportion of children with ASD who have ID and highlights the need for further research to fill a significant gap regarding the profile of academic abilities of students with ASD-ID.

The Montessori method was originally developed from an examination of children with cognitive disabilities. Numerous studies have explored the application of Montessori principles with typically developing children and adolescents across different educational settings. However, despite its original interest in children with cognitive disabilities, there has been a limited number of systematic reviews specifically addressing its impact on these children. We conducted a systematic review of quantitative research based on a search of the literature on the effects of the Montessori educational approach in teaching academic and non-academic skills to children and young people with intellectual disabilities (IDs) and autism. A search was conducted of seven bibliographic databases: Embase, PubMed/MEDLINE, PsycINFO, Cochrane Library, Ebscohost, Proquest, and Scopus, until 31 October 2024. We identified 7165 reports, 3 of which meet the inclusion criteria for the review. The selected studies reported improvements in the areas investigated, including motor skills, perceptual abilities, cognitive development, and self-care, confirming the effectiveness of the Montessori methodology. Although there are few experimental studies available, these findings provide valuable operational insights. They suggest that we can return to the roots of the method, which was originally designed for children with mental disorders. An experimental approach to this time-honored method could enhance its application in neurodevelopmental disorders, maximizing autonomy and inclusion while improving the quality of life for individuals with disabilities.