This study investigates special teachers and paraprofessionals use of formative assessment for students with moderate to severe intellectual disability (ID). It draws on findings from school develoment projects that contains lesson observations, collection of lesson plans and interviews special teachers and paraprofessionals in four elementary schools in Sweden. A recent project (Anderson & Östlund, 2017) reported that there is still a lack of knowledge in working with formative assessment in the education for students with moderate to severe intellectual disability (ID in Swedish schools. Participants in the study presented represent a wide diversity in the level of education and experience. The special teachers had an academic education - about 5 years - however the paraprofessionals education varied a lot from some years of college education to no education at all. This diversity in the group of professionals has been a challenge in all four projects. The group of students in the participating classes, about 30 students, is in different ages from 6 years to 16 years and has varied forms of disabilities and comes from different cultures and socio-economic backgrounds.The results shows that the participants developed their feedback techniques, providing feedback on a task level, process level and self-regulation level. Another important improvement was the development of  multimodal materials to support the students to get access to the curriculum (fx. Video modelling, visual aids). From an overall perspective the different projects provided a change in teaching culture in all four schools: from a focus on ”taking care” of the students to working with the students PZD in all kind of learning situations.