Why do intervention lists keep growing instead of shrinking?
You’ve invested in intervention staff, catch-up sessions and new programmes, yet every assessment point reveals another group of pupils who need support.
This often isn’t an intervention problem. It’s a core teaching problem, and strengthening it is one of the most powerful levers school and trust leaders have for closing gaps before they form.
When core teaching is strong, intervention becomes targeted support for the few who need it, not a revolving door for pupils who should have succeeded first time.
Here are five signs your core teaching needs strengthening, and the approaches leaders are using to turn things around.
Where core teaching fits in your support model
Many English schools already work with a tiered logic. The Education Endowment Foundation’s pupil premium guidance describes three layers: high-quality teaching for all, targeted academic support for some, and wider strategies for particular barriers. The SEND Code of Practice likewise treats high-quality teaching as the first response to pupils who may have additional needs. The US framework this article draws on, the Multi-Tiered System of Supports (MTSS), is more formalised, but the principle is the same.
When leaders look to improve outcomes, attention often goes to targeted and specialist support. But if core teaching isn’t strong, you spend intervention budget fixing what could have been prevented. Getting core teaching right from the start is among the most cost-effective investments you can make.
Sign 1: Your curriculum covers the content but overwhelms working memory
Curriculum plans can cover every National Curriculum objective, but coverage isn’t the same as instructional design. When lessons introduce too much new information at once without enough scaffolding, even capable pupils can’t retain what they’re learning. That isn’t a pupil capacity issue. It’s a cognitive load issue.
Cognitive load theory tells us that working memory is limited. Pupils can only process so much new information before they become overwhelmed. Without explicit instruction, systematic practice and careful sequencing, a well-intentioned curriculum can work against learning.
What this means for leaders: When reviewing curriculum resources, assess how well they manage cognitive load. Explicit, systematic instruction with cumulative practice should be built in, not left to individual teachers to invent. Ask suppliers how their programme manages cognitive load, whether instruction is explicit and sequenced, and whether practice is scaffolded and cumulative. Programmes that embed these principles reduce the burden on teachers to reinvent research-informed design, which matters for workload as well as consistency.
Prioritise [evidence-based programmes](link TBC) that build in explicit, systematic instruction with scaffolded practice. This is good pedagogy and sensible resource allocation.
Sign 2: Reading gets strategic attention, but early maths gets less
Early reading has had sustained national focus in England, with a clear emphasis on systematic synthetic phonics and the DfE’s Reading Framework. Many teachers can now articulate the research behind how children learn to read.
The question for leaders is whether early maths has the same clarity of purpose in your school or trust. Far fewer teachers may feel confident explaining the research behind early number development, such as number sense, subitising and comparing quantities, or how mathematical reasoning connects to executive function. National resources exist, including the DfE’s Ready-to-progress criteria and NCETM materials. But using them well requires deliberate leadership attention.
If pupils leave the early years of primary with stronger reading foundations than maths understanding, that is worth finding out sooner rather than later.
What this means for leaders: Be explicit about your commitment to evidence-informed teaching in both domains. Just as you evaluate reading programmes against the evidence base, evaluate maths programmes for explicit teaching of foundational concepts such as number sense and problem-solving. When reading and maths approaches complement each other, you build interconnected foundations rather than competing priorities.
Bring the same strategic focus to early maths that you’ve brought to early reading. Both deserve evidence-informed core teaching.
Sign 3: You have high-quality assessment data, but it isn’t shaping core teaching
Many schools and trusts invest in standardised reading and maths assessments, alongside statutory checks such as the Year 1 phonics screening check. You may have dashboards full of standardised scores and percentile rankings. But is that data informing everyday teaching decisions, or only identifying who needs intervention?
Assessment data is most powerful when it tells teachers what pupils are ready to learn next, not just what they’ve missed. When scores are connected to clear instructional starting points, teachers can adapt whole-class teaching to meet pupils where they are.
What this means for leaders: When evaluating teaching programmes, ask whether they work with your assessment approach. Can teachers use your assessment data to place pupils at the right starting point? Beyond placement, look for reporting that lets teachers track progress against the National Curriculum or your trust’s curriculum.
Choose materials that connect assessment data to practical next steps and offer transparent progress reporting, so your investment in testing translates directly into better teaching.
Sign 4: You’re investing in intervention, but gaps keep refilling it
This is the costliest sign. You’ve funded intervention staff, bought programmes and added catch-up time, yet each assessment point reveals a new cohort who need support.
The problem isn’t that intervention doesn’t work. It’s that core teaching isn’t preventing the need for it in the first place. When teaching is inconsistent, under-resourced or not informed by research, you end up treating symptoms rather than root causes.
What this means for leaders: Audit what you spend on intervention against what you invest in core teaching. Include staffing, programmes, training and timetable time. Understanding the true cost of intervention gives you a baseline and shows where prevention might deliver the greatest return. Strengthening core teaching won’t remove the need for intervention, but it should reduce how many pupils require it.
Rebalance your investment. Strong core teaching is among the highest-leverage and most cost-effective decisions you can make.
Sign 5: Teachers have autonomy, but no shared definition of high-quality teaching
Professional autonomy is valuable until it becomes inconsistency. When every classroom operates differently, pupils experience very different quality of teaching depending on which class they’re in. In a trust, that variation can run across schools too. That isn’t equitable.
Leaders sometimes hesitate to define core teaching too tightly, worried about morale or stifling creativity. But clarity isn’t rigidity. Teachers benefit from a shared understanding of what evidence-informed teaching looks like, and from access to high-quality materials that reflect it.
What this means for leaders: Coherence doesn’t mean removing teacher voice. It means ensuring every pupil, whichever class they’re in, receives well-sequenced, research-informed teaching. A shared approach, supported by strong materials, gives teachers a firm foundation and frees them to focus on responsive teaching.
Define your non-negotiables for core teaching and provide high-quality materials, with evidence you’ve scrutinised, to support implementation.
The case for investing in core teaching
When core teaching is strong, fewer pupils need intervention and every pound spent on support goes further. The question isn’t whether to invest, but how soon you can make it stronger.
Literacy and numeracy develop hand in hand, particularly in the early years of primary. Strengthening both foundations together with evidence-informed programmes doesn’t have to add to workload. It creates classrooms where every pupil has the chance to thrive.
To explore the research and strategies behind strong core teaching, download our free guide, The Early Years Advantage: Building Strong Foundations in Literacy and Numeracy.
