Opportunity Cost

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We’re gonna get there. One step at a time….

Big idea 🍉

Last snack, we looked at a bunch of popular but ineffective SEN interventions. To fully appreciate the problematic nature of this, we need to unpack what Dylan Wiliam calls the most important idea in education: opportunity cost.

Take coloured overlays. Despite widespread claims, repeated studies suggest they tend not to help dyslexic readers. But they don't seem to do any harm either. So what's the problem?

The problem is that education is a zero-sum game. Schools only have so much time and energy to go around. If we choose to do one thing, it means we can't do another. And when one option is more effective than the other, that choice costs our students.

For example, the hours we pour into detailed marking feel productive, but if students barely act on it, that time could have been better spent on crafting a clear explanation.

The challenge is: we're not great at considering opportunity cost, mostly because is invisible. We tend to weigh what's in front of us, not the thing we're giving up, and only reconsider once the alternative is spelled out.

This is why, for Wiliam, "what works" is the wrong question. Everything works somewhere, and nothing works everywhere, and almost anything works a little. Instead we should ask: what use of our time produces the greatest benefit for students?

In short, if it's not adding, it's subtracting. Every minute spent on something ineffective, like overlays, is a minute not spent on something that works, like structured phonics. The overlays don't hurt our students, but the time we spend on them does.

Opportunity cost is an idea we need to get better at, if we're truly going to become a more evidence-informed profession. Not just knowing what works, but what works best.

🎓 For more, check out this analysis of the cost of teacher time.

Summary

• Even when a practice does no harm, it still has a cost: the time and energy it takes could have gone to something more effective.

• We miss this because the alternative is invisible... we weigh what's in front of us, not what we're giving up.

• So the question to ask isn't "does this work?" but instead: "what works best? (for the time we have available)"

Little updates 🥕

• Study on worked examples → suggests they may improve learning through self-explanations, especially for learners with lower prior knowledge.

• Article on attainment inequality → suggests outcome gaps are partly linked to widening working-memory differences during adolescence.

• Report on improving attendance → argues effective practice involves building inclusive cultures, proactive communication & individualised support.

• Summary of learning research → highlights practical approaches to retrieval, worked examples & self-regulation while challenging common learning myths.

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