The Planning Fallacy

Hey

It’s nice to wake up in a place of happy memories: we should do more of that. But first…

Big idea 🍉

As teachers, we’re subject to the IKEA effect: we tend to overvalue what we make ourselves. But that’s not the only cognitive bias at play when it comes to planning...

Everyone who’s been a teacher (or teacher trainer) knows it intuitively. Left to our own devices, we tend to run over. We plan it, we’re sure it fits, then the bell goes and there’s still a chunk left.

This is the Planning Fallacy. We systematically underestimate how long things take. Lessons, training, even planning itself.

Why? Well, it’s that pesky Expert-Induced Blindness rearing its head again. Because we know the material inside out, it feels quick when we roll it around in our mind. However, the outside world doesn’t move at that pace. And so we overshoot.

It’s not just teachers either. In general, when students or other humans face big projects, we run over about 90% of the time. Over-optimism is baked into our species. If you’re not convinced, track your lessons for a month to see.

And obviously: all this hurts learning. We lose vital parts of lessons (assessment, review), and over the course of a year, we develop deep curriculum debt.

The problem is that just knowing about this bias often isn’t enough to change our behaviour. We also need to build better habits. This means factoring a buffer into our lessons as standard (and then being pleasantly surprised if we ever actually get to use it).

Achieve more: plan to do less.

🎓 For more, check out this paper on teacher’s blind spots.

Summary

• The planning fallacy means teachers often underestimate how long lessons, explanations and tasks will take.

• This is exacerbated by expert-induced blindness: because this content feels familiar to us, we assume learners can process it just as quickly.

• Overcoming this requires more than awareness; we need to approach our planning with intentional time buffers.

Little updates 🥕

• Study of physical activity & cognition → highlights that activity may support girls’ attention through perceived fitness, while boys showed no clear links.

• Study of parental mindsets → finds parents reframing failure may support student-teacher relationships, particularly for lower-achieving learners.

• Article on teachers’ inclusion attitudes → finds positive views of inclusive teaching do not consistently improve attainment.

• Paper on teacher burnout → links burnout to greater absence, poorer teacher-learner interactions & lower student motivation, but not clearly to attainment.

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