Although many schools in the Netherlands have purchased adaptive learning systems (ALSs) to reduce workload and improve differentiated instruction, the use of ALSs with teacher dashboards in the classroom does not in itself necessarily improve differentiated instruction. The question is, what skills and knowledge do teachers need to provide differentiated instruction with the help of ALSs with teacher dashboards and how does this differ from a context in which such technologies are not used? By means of a cognitive task analysis, consisting of classroom observations, interviews, and several expert meetings, teachers' skills, and knowledge necessary for providing differentiated instruction when using teacher dashboards and ALSs were disentangled. These findings were compared with the skills and knowledge needed by teachers providing differentiated instruction without these tools. Results show that teachers' dashboards can support teachers when providing differentiated instruction by providing up-to-date information about students' progress. Nevertheless, coping with the new information provided on the dashboards also requires new skills and knowledge such as interpreting information from the dashboard and understanding how the information in the ALS is calculated. Although there are some differences, the core principles of differentiated instruction--being goal-oriented, continually monitoring, adapting instruction and assignments, being ambitious, stimulating students' self-regulation--are critical for high-quality differentiated instruction regardless of the available tools in the classroom.