## Key Ideas > [!abstract] Core Concepts > > - **Limited evidence for effectiveness**: Differentiation generally does not solve inequitable outcomes it seeks to address (Caro et al., 2016; Brighton et al., 2005; Smale-Jacobse et al., 2019) > - **Strongest positive evidence**: Small-group interventions (2-4 students) with schema-based instruction show g = 0.37 to 0.41 for students with mathematics difficulties (Jitendra et al., 2018, 2021) > - **Address versus accommodate**: Build missing skills rather than work around deficiencies (Hattie, 2009) > - **Thin evidence base for Years 7-12**: Fewer than 15 high-quality studies on Years 7-8 mathematics; Years 9-12 consists of small-scale quasi-experimental studies with researcher-made tests (Smale-Jacobse et al., 2019) > - **Focus on [[responsive teaching]]:** No approach clearly outperforms high-quality whole-class explicit instruction. Implementation barriers and workload costs often outweigh theoretical benefits. ## Definition **Differentiation**: Practice of tailoring instruction to meet diverse student needs through adjusting outcomes, tasks, or support based on prior knowledge and abilities (Tomlinson, 2001). ## Connected To [[Ability Grouping]] | [[Low-Floor High-Ceiling]] | [[Scaffolding]] | [[Prior Knowledge]] | [[Responsive Teaching]] --- ## Evidence summary | Approach | Effect Size | Grade Level | Key Finding | Evidence Quality | | ------------------------------------------------- | ---------------------------------------------------- | --------------------------------- | ----------------------------------------------------------------------------------------------- | --------------------------------------------------- | | **Small-group RTI (2-4 students)** | g = 0.37 (Jitendra 2018)<br>g = 0.41 (Jitendra 2021) | Secondary (LD/MD)<br>K-12 Tier 2 | Positive effects for students with mathematics difficulties; schema-based instruction effective | Meta-analyses of experimental studies | | **Word problem interventions** | g = 0.71 | Upper elementary & secondary (MD) | Larger effects for targeted problem-solving instruction | Meta-analysis (Myers 2022) | | **Within-class ability grouping (adapted)** | d = +0.25 | K-12 | Only works when instruction substantially adapted to groups | Meta-analysis (Lou 1996) | | **Within-class ability grouping (no adaptation)** | d = +0.02 | K-12 | Simply grouping students achieves nothing | Meta-analysis (Lou 1996) | | **Within-class ability grouping (aggregate)** | g = 0.19 to 0.30 | K-12 | Effects only appear with instructional adaptation | Synthesis of 13 meta-analyses (Steenbergen-Hu 2016) | | **Within-class ability grouping (low achievers)** | Negative effects (p = 0.002) | Primary | Low-ability students harmed by separation from peers | Meta-analysis (Deunk 2018) | | **Generic differentiation training** | d = +0.509 (excluding outliers) | Secondary (all subjects) | Highly variable (d = -0.088 to +1.461); requires extensive external support | Systematic review (Smale-Jacobse 2019) | | **Differentiation vs traditional** | Inconclusive | Year 7 maths | Two independent trials showed inconsistent results; implementation problems | Quasi-experimental (Williams 2012) | | **Student-oriented instruction (PISA)** | Negative association | All OECD systems | "Give different work to classmates" negatively associated with maths scores in all 62 systems | Large-scale correlational (Caro 2016) | | **Technology-supported adaptive practice** | d = 0.10 | Various | Small sustained effects at low cost | RCT (Roschelle 2020) | | **Reduced content demands** | No direct evidence;<br>indirect evidence negative | Years 7-12 maths | Reduces opportunity to learn; low achievers benefit from full curriculum access | Indirect evidence (Lou 1996; Deunk 2018) | | **Universal Design for Learning** | Positive for engagement;<br>no impact on outcomes | Various | Effects on process but not learning outcomes | Meta-analysis (Capp 2017) | | **Low-floor high-ceiling tasks** | No quantitative evidence | Various | Theoretical support for equity; no controlled studies | Advocacy (Boaler 2016) | ## Approaches to differentiation Teachers differentiate in three ways. Differentiation by outcome assigns identical open-ended tasks to all students whilst expecting varying complexity in responses. Differentiation by task provides different activities based on perceived ability levels, with less able students receiving scaffolded tasks and more able students receiving complex tasks. Student choice is generally unproductive because students rarely make informed decisions weighing task demands against learning needs. ## What works Small-group interventions (2-4 students) using schema-based instruction and explicit teaching show consistent positive effects (g = 0.37 to 0.41) for students with mathematics difficulties (Jitendra et al., 2018, 2021). Key components include teaching underlying problem structures, explicit and systematic instruction with modelling and feedback, and small-group delivery outside regular classroom instruction. For Year 7 specifically, Jitendra et al. (2013) conducted a cluster-randomised controlled trial with 82 teachers and 806 students. Schema-based instruction on proportional reasoning produced positive effects maintained at nine-week follow-up, though effects appeared on proportional reasoning measures rather than general mathematics achievement. Within-class ability grouping works only when instruction is substantially adapted to group needs (d = +0.25). Without adaptation, effects are d = +0.02 (Lou et al., 1996). Simply placing students in ability groups achieves nothing. Low-floor high-ceiling tasks provide an alternative where all students receive the same task with an accessible entry point and extension opportunities (Boaler, 2016), though there is no evidence to support this. Technology-supported adaptive practice shows small sustained effects (d = 0.10) at low cost when embedded in instruction (Roschelle et al., 2020). ## What doesn't work Caro et al. (2016) analysed PISA 2012 data across all 62 OECD education systems. Student-oriented teaching (measured as "teachers give different work to classmates who have difficulties learning and/or to those who can advance faster") was negatively associated with mathematics scores in every country individually. Ability grouping without instructional adaptation shows near-zero effects overall (d = +0.02) and harms low-ability students (Deunk et al., 2018; Lou et al., 1996). Low-ability students learned more in mixed-ability groups than homogeneous groups (Lou et al., 1996). Deunk et al. (2018) found within-class ability grouping showed significant negative effects for low-ability students (p = 0.002). Reduced content demands have no supportive evidence and indirect evidence suggests harm. Lou et al. (1996) demonstrated that low achievers learned more when kept with higher-achieving peers, implying access to full curriculum matters. High-performing systems including Finland, Japan, and Estonia maintain unified mathematics curricula without content reduction through Year 9. Generic differentiation training shows highly variable results (d = -0.088 to +1.461) and often requires extensive external researcher support (Smale-Jacobse et al., 2019). Williams (2012) found differentiation versus traditional instruction produced "inconsistent" and "inconclusive" results in Year 7 mathematics, with implementation difficulties even in research conditions. ## Evidence base limitations ### Years 7-8 mathematics The evidence base is thin. Smale-Jacobse et al. (2019) identified just 12 empirical studies across all secondary subjects. For Years 7-8 mathematics specifically, comparative evidence is nearly absent. Most differentiation research examines primary grades and many studies lack control groups. Francis et al. (2017-2019) conducted the most relevant UK study, a large-scale randomised controlled trial across 139 schools examining setting versus mixed attainment in Years 7-8. ### Years 9-12 mathematics The evidence base consists primarily of small-scale quasi-experimental studies with researcher-made tests. Most studies lack randomisation, use short intervention periods (2-12 weeks), and show inflated effect sizes typical of proximal measures rather than standardised assessments. These studies share methodological limitations: extremely short intervention periods, small samples (32-60 students), researcher-made tests administered immediately post-intervention, and lack of random assignment. Teachers in experimental groups received differentiation training, confounding pedagogical knowledge with instructional approach. No studies followed students beyond immediate post-test, and none used standardised achievement measures. Positive findings likely reflect researcher effects, short-term proximal gains, and measurement bias rather than sustained learning improvements. Ziernwald et al. (2022) reviewed 49 studies on differentiation's impact on high-achieving students in mixed-ability classrooms. Teachers typically did not use differentiation for high-achieving students proactively or regularly. PISA 2012 data showed only 30% of OECD students reported teachers gave different work in most mathematics lessons, ranging from 13% in France and Italy to 62% in Sweden. Implementation barriers include lack of teacher knowledge, limited school-level support, and restricted pedagogical repertoire. ## Address versus accommodate A critical distinction separates effective support from learnt helplessness. An address approach uses intensive intervention targeting specific deficits. Through systematic instruction, students develop essential skills and build capability they currently lack. An accommodate approach works around deficits through adjustments or technology. Students never develop capability and the gap widens permanently. Address approaches suit the vast majority of students capable of learning the skill with proper instruction. Accommodate approaches suit only diagnosed cognitive impairments that genuinely prevent skill acquisition. Low achievers benefit from instructional adaptation, not from separation or content reduction. Effective support maintains high expectations and full curriculum access whilst providing additional scaffolding, time, and explicit instruction. ## Implementation challenges Brighton et al. (2005) found few effects for differentiation on student achievement, and those identified were weak. Teachers failed to implement the model effectively due to large class sizes, limited resource materials, lack of planning time, lack of collaboration structures, and increasing responsibilities. The authors concluded that differentiation might work in ideal environments but remains otherwise impractical. [[Implementation fidelity]] problems appear consistently. Vogt and Rogalla (2009) found that professional development increased planning competency but failed to improve classroom implementation. Prast et al. (2018) reported small positive effects in Year 1 of a Dutch primary schools intervention, but effects disappeared in Year 2. Differentiation imposes increased workload with weak evidence bases. Pozas et al. (2020) found teachers "implement more frequently those single differentiated instruction practices that require less preparation" due to "high workload that teachers face worldwide." The Western Australian Education Department's 2023 report identifies "pedagogical fads and fashions" as creating routines that "do not achieve the intended educational goals." The evidence base suffers from definitional inconsistency. "Differentiation" operationalised as ability grouping shows near-zero or negative effects; operationalised as schema-based small-group instruction shows positive effects; operationalised as intensive tutoring shows larger effects. These are fundamentally different practices, making blanket claims about "differentiation effectiveness" meaningless. ## Practical implications for teaching Use whole-school targeted support structures rather than classroom differentiation. Small-group interventions (2-4 students) outside regular instruction show the strongest evidence (g = 0.37 to 0.41) for students with mathematics difficulties. These interventions require schema-based instruction, explicit teaching with modelling and feedback, and sustained support to address effect fade-out. Within-class ability grouping only works when instruction is substantially adapted to group needs (d = +0.25). Grouping alone achieves nothing (d ≈ +0.02). Low achievers show better outcomes when maintained with peers in mixed-ability groups with full curriculum access rather than separated or given reduced content. Use the same high-quality tasks with built-in accessibility and extension for all students. Low-floor high-ceiling tasks provide entry points and extension opportunities within a single task. Technology-supported adaptive practice offers individualised practice opportunities without fragmenting classroom teaching (d = 0.10). Build missing skills rather than work around them. Address approaches using intensive intervention develop capability; accommodate approaches widen gaps permanently. Most students are capable of learning skills with proper instruction. Monitor achievement impacts carefully across all student groups. Generic "differentiation" shows highly variable results (d = -0.088 to +1.461) and often requires extensive external support. No approach clearly outperforms high-quality whole-class explicit instruction. 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