My most memorable science lesson at primary school? Stinging nettle soup. I can remember Mr Nielson sending us outside to carefully pluck young stinging nettle leaves. And then coming back into the lab and watching him rolling up such a leaf, rubbing it between his fingers and putting it in his mouth. He happily chewed away without stinging his tongue. I was dumbfounded. As a rambling kid, I’d quickly learned to rub dock leaves on my stung legs to relieve the nettle’s stabbing pain. How on earth could he get away with this?

Rolling and rubbing the leaves, Mr Nielson explained, removed the sting. I tried it, and thankfully, he was right.

Next, we boiled our stinging nettle leaves in a beaker of water above a Bunsen burner for a few minutes. We removed them with tongs and put them on a paper towel to cool down. Tasty? Not really in my ten-year-old mouth. Although I liked Popeye, I did not yet appreciate anything that tasted like spinach.

So why do I remember this lesson over 40 years later? Because it taught me that things which seem counterintuitive can nevertheless be right.