Misuse of the equals sign: An entrenched practice from early primary years to tertiary mathematics

In mathematics we frequently need to express equality between expressions. Robert Recorde, born in Wales in about 1510, is credited with inventing the equals sign that we use today. Up until this time, equality was expressed in words. Recorde's first use of the equals sign was in 1557 in The Whetstone of Witte. Translated into modern English, Recorde's explanation of his equals sign reads: "And to avoid the tedious repetition of these words 'is equal to' I will set as I do often in work, use a pair of parallel lines of one length, thus: =, because no 2 things can be more equal". This article begins with a brief look at the the broader aspect of symbolic literacy in mathematics. This is followed by an investigation of the origins of misuse of the equals sign among primary and junior secondary students and first year undergraduate mathematics students’.