AfterMaths: Maths Misused - Our Favourite Everyday Errors

In this week’s Aftermaths, Jon and Becky dive into the wonderfully frustrating world of mathematical misuses in everyday life, inspired by a brilliant email from listener Sam Asplund, a Year 4 teacher and maths lead from Ketten Primary School.

After a pupil requested a “cheese square” during snack time — while pointing out that Dairylea “triangles” aren’t truly triangles at all — Jon and Becky go down a joyful rabbit hole of everyday maths errors. From curved-edged cheese sectors to supermarket statistics, they explore the misconceptions we see “in the wild” far more often than we’d like.

This week’s highlights include:

🧀 When a Triangle Isn’t a Triangle

Sam’s pupil correctly notes that Dairylea “triangles” have a curved edge — making them not triangles at all. Cue a debate about polygons, sectors, and whether “Dairylea Cylindrical Sectors” will ever catch on.

🎲 Probability Problems: The Gambler’s Fallacy

Becky’s first maths misuse: believing that something is “due” to happen simply because it hasn’t happened yet. From dice rolls to roulette wheels to lottery numbers, the misunderstanding is everywhere.

📊 Averages That Mislead

Jon unpacks how mean and median can tell very different stories — and why politicians love using whichever version suits them best. If you've ever wondered why the “average salary” feels inflated… this segment will speak to you.

🔗 Correlation ≠ Causation

Becky explores how easily people mistake coincidence for cause — from homework to exam results, leafy diets to lifestyle habits, and even the old myth about storks bringing babies.

📈 Misleading Percentages

Jon rounds things off with the problem of tiny samples, big headlines, and percentages designed to impress rather than inform. (“Burglaries up 200%!” doesn’t mean what you think.)

🎧 Interview Debrief: Rob Eastaway

Becky shares her takeaways from Jon’s interview with Rob Eastaway, including:

• Why written methods rarely feature in “real-world maths”
• How puzzles inspire genuine mathematical thinking
• The importance of estimation
• Making space for curiosity, conjecture and open-ended exploration

💌 Listener Call-In

Got a favourite maths error you’ve spotted in the wild? Email: primarymathspodcast@twinkl.co.uk — Jon and Becky would love to feature it.