Humour in the classroom creates a receptive frame of mind and highlights important information. The exchange of jokes and riddles between children also has important social functions.
Research undertaken in primary schools in Kent suggests additional benefits. Many forms of humour help familiarise children with mathematical concepts and can even encourage mathematical calculation.
At least five main categories of maths jokes and riddles have been identified. These relate to number, time, size, shape and pattern. The following example is a popular number riddle: "There were 10 copycats sitting in a tree. Three fell out. How many were left?" The answer is none - after all, they were copycats. This particular riddle is often extended into a game. The questioner randomly substitutes cats for copycats and varies the number of felines falling from the tree. The audience must understand the rules of subtraction, as well as the rules of riddling.
Children's number riddles also involve humorous play on the concept of sets: "Name five things with milk in them."
"An ice cream, a milk shake, a piece of cheese . . . and two cows."
Sometimes, a level of statistical analysis is required: "Why do white sheep eat more than black sheep?" "Because there are more white sheep."
Jokes and riddles involving time are a popular form of primary humour:
"Doctor, doctor, I've only got 59 seconds to live."
"Now just wait a minute."
The mental calculation involved in providing a mathematically correct response is often insulted by the simplicity of the riddle's answer: "How many seconds in a year?" "Twelve: January second, February second . . ."
Size humour often involves the pairing of two incongruous ingredients, plus an element of estimation: "What do you get when you cross a hedgehog with a giraffe?" "A 20-foot toothbrush."
In the shape category, jokes and riddles encourage children to explore the dimensional world: "How many sides has a table tennis ball?" "Two: an inside and an outside."
Pattern humour lies behind many primary favourites: "What goes 99 plonk, 99 plonk?" "A centipede with a wooden leg."
Joke-telling may have particular benefits in the formative years of a child's mathematical development. The Mathematical Association has identified several aspects of early speech that are crucial to the foundation of mathematical thinking. These include attribute words (big, little, blue), position words (on, in, under), comparison words (bigger, smaller, more), question words (who, why, where) and connectives (but, because, and).
All these speech forms are characteristic features of children's earliest riddles: "What's big and red and eats rocks?" "A big red rock-eater."
"What did the big chimney say to the little chimney?" "You're too young to smoke."
"Why did the chicken cross the road?" "Because it wanted to get to the other side."
This classic brand of humour appears to encourage young children to explore rudimentary mathematical concepts and vocabulary.
Whether there is a legitimate place for jokes and riddles in the formal maths is an interesting question - perhaps one that educators will wish to explore for themselves. In the meantime, even the most feeble joke may encourage mathematical thinking, so don't knock-knock the corny playground punchline.
Louisa Burville-Riley is a freelance psychologist and teacher