The deliberate adaptation of teaching to address the different levels, needs, interests, and learning profiles within a single class. Rather than delivering the same content in the same way to every learner, the teacher modifies what is taught, how it is taught, or what learners produce so that each student works at the edge of their competence.
The term comes primarily from mainstream education through Carol Ann Tomlinson's work at the University of Virginia (1999, 2001, 2014). In ELT, differentiation overlaps heavily with mixed-ability teaching, but the concept is broader: it applies to any classroom, not just obviously heterogeneous ones, because no two learners are identical.
Tomlinson's model identifies what the teacher can differentiate and what drives the differentiation:
Content: what students learn. Not lowering the standard for weaker learners, but adjusting the entry point. A vocabulary lesson might give lower-level learners 8 target words and higher-level learners 12, or provide different reading texts at different levels on the same topic.
Process: how students learn. The activities, tasks, and support structures. Some students work with a model text and sentence starters; others work from a prompt alone. Some students discuss before writing; others go straight to writing. The learning process is varied to match how different learners work best.
Product: what students produce to show learning. Some students write a paragraph; others write an essay. Some present orally; others create a poster. The output format is adjusted so that learners can demonstrate understanding at their own level without being held to a uniform format that advantages some and disadvantages others.
Readiness: the student's current level of knowledge and skill relative to the learning objective. This is the most common driver in ELT: learners at different proficiency levels need different levels of challenge and support.
Interest: what motivates and engages the student. Allowing topic choice within a task (write about any hobby, not a prescribed one) differentiates by interest without requiring different materials.
Learning profile: how the student learns best. This includes learning preferences (visual, auditory, kinesthetic), working style (individual vs. collaborative), and cognitive style. More contested than readiness and interest; "learning styles" as a fixed trait has been largely debunked (Pashler et al., 2008), but varying the mode of activity is still good practice.
Tomlinson later added a fourth trait, affect: the emotional state and confidence of the learner, which influences engagement and risk-taking.
In language teaching specifically, key references include:
Tiered tasks: the same core activity at different levels of difficulty. All students read the same text, but comprehension questions are graded: literal questions for lower levels, inferential for higher. See Mixed Ability for detailed examples.
Flexible grouping: varying group composition across activities. Same-level groups for targeted practice, mixed-level groups for peer scaffolding. Neither should be permanent; rotating prevents labelling.
Task choice: offering two or three versions of a task and letting students choose. This respects autonomy and naturally differentiates by readiness without the teacher having to assign levels publicly.
Graduated support: providing scaffolding that can be used or ignored. Word banks, sentence starters, model answers, and graphic organisers are available for those who need them, invisible to those who don't. The support is optional, not imposed.
Extension activities: core task for all, with a "challenge" or "bonus" layer for early finishers. "If you've finished, now rewrite your paragraph without looking at the model." This keeps fast finishers productive.
Open-ended tasks: activities where the output naturally varies by level. "Write about your weekend" produces A2 output from A2 students and B2 output from B2 students. Discussions, creative writing, and problem-solving tasks are inherently differentiated.
Compacting: for students who already know the material, the teacher "compacts" (skips or abbreviates) the instruction phase and moves them straight to practice or extension. This avoids wasting the time of stronger learners on content they have already mastered.
Differentiation is not the same as individualised instruction. Individualised instruction (one learner, one plan) is impractical in most classroom settings. Differentiation works at the group level by identifying 2–3 broad clusters of need and adjusting accordingly. The goal is "good enough" adaptation, not perfect personalisation.
Differentiation is the practical application of Learner-centredness in heterogeneous classrooms. It operationalises Vygotsky's ZPD: each learner should be working just beyond their current level, with appropriate scaffolding. Needs Analysis is the diagnostic step that informs differentiation: you cannot differentiate effectively without knowing who your learners are. Materials Adaptation is the skill of modifying published materials to serve differentiated purposes, such as adapting a coursebook text for two levels.