Background and aims Teachers serve as critical communication partners for students with intellectual disability (ID) who face communication difficulties. However, teachers may lack sufficient training in using communication partner strategies and augmentative and alternative communication (AAC) in the classroom. This study aimed to explore teacher application of a communication partner intervention (AKKtiv ComPal) in schools for students with ID. Methods Video observations were conducted at four schools during a teacher-led group activity at pre- and postintervention, with follow-up 7 months later, focusing on communication partner strategies and AAC use applied as a universal approach in the classroom. Differences and similarities in intervention application and contextual factors that may influence teacher application were investigated using a multiple case study approach, in which the four teachers and their contexts served as the four examined cases. Results All cases increased the access to communication boards in the classroom and used more augmented input and responsive strategies following intervention. Follow-up measures revealed variability in augmented input and sustained or more use of responsive strategies. Despite increased strategy use, access to communication boards remained inconsistent, and augmented input was used with variability across observation minutes. Influencing factors to teacher application seemed to be classroom setups (such as having a table), previous AAC skills, student characteristics, and postintervention efforts such as repeating the intervention or participating in follow-up sessions. Conclusions This study demonstrates that classroom teachers for students with ID can use augmented input and responsive strategies as a universal design approach in the classroom following the AKKtiv ComPal intervention. However, teachers may utilize the strategies somewhat differently, partly influenced by their contextual factors. Implications The findings suggest that while teachers for students with ID can successfully use communication partner strategies in the classroom, their use of augmented input should be nurtured over time to ensure sustained use and possibly improve consistency. Additionally, adapting to the physical environment of the classroom is crucial to optimize the application of these strategies.