After an introduction to new material, some students have mastered it and are ready to move on, while others haven’t. Before any differentiation is attempted, however, it is essential that both the students and the teacher have feedback about their level of readiness to move on. A quick ungraded check-up may be sufficient to tell you that differentiation is called for. It will also inform each student about what he needs to do next.
For a student who has mastered the material, some form of enrichment is called for. This can be a more sophisticated challenge regarding the same topic that was just completed, or it can be an introduction to a different topic altogether.
For a student who hasn’t yet mastered the material, remediation is called for. The actual form of this work will depend entirely on what type of material is being learned. For skills-based material, more practice may be required. For concepts-based material, more reading or analysis or discussion of the concepts may be optimal.
Both enrichment and remediation can be done by individual students or small groups. Both can be done with or without your participation. However, if a student is working with other students or with you, he should ideally do another check-up afterwards to determine whether he has mastered the material independently.