Did you have a 6 inch (15 cm) ruler in your pencil case when you were at school? Perhaps you still keep one in a desk drawer?
But have you thought about the history of the ruler?
Instruments to help us draw straight lines and measure things have been around for thousands of years – the Indus Valley civilisation used ivory rulers as long ago as 1500 years BC.
Original measurements were based on human anatomy and derived from the length of the forearm, hand or finger, according to Babylonian, Egyptian and Hebrew records. The British imperial measurement of feet and inches was derived from the length of a foot (as you might guess) and the width of fingers. But a foot used to be around 11 inches in length before feet evolved to become 12 inches long!
Rulers were important in schools and useful for maths lessons and drawing accurate scientific diagrams, as well as underlining hand-written notes. But today, computers have made the ruler a little less important in the classroom.
Rulers had a dark side in times gone by, particularly in the strict Victorian Age. They were used to hit children’s hands as a form of punishment. Even in the middle and late 20th century, teachers used them to discipline young children in primary schools (older children got heavier punishments with canes and slippers across their bottoms!)
Having your hand whacked with a wooden ruler was quite sharp, especially if the teacher rapped the back of the hand instead of the palm, and the stinging pain reduced children to tears.
But corporal punishment was made illegal in UK state schools in 1989 (1999 in private schools) and by then ruler punishments had died out anyway. So rulers are now just benign additions to your desk drawer- let’s just get that straight!