![]() ![]() The credit for creating a number line to show numbers less than 0 is usually given to the Englishman John Wallis. His choice of 32 insured, at least for his time, that all temperatures would be numbers greater than 0. He seemed to know about using a number line for temperatures, but did not have a way to describe a reading less than 0. However, by the 1600s, mathematicians were aware of numbers that they could not easily explain with “real things.” It is interesting to note that Fahrenheit chose 32 as the number for the freezing point of water when he created the first accurate thermometer. It was good for measurement as well as calculations that involved “straight forward” operations such as addition and multiplication. ![]() The rope was a visual tool that worked well with real things. The rope was one single length so it could be used to measure buildings, walls, or fields. In the picture, Egyptian rope measurers have formed a triangle with 3 spaces, 4 spaces, and 5 spaces respectively along each side. They tied knots equal distance along a rope that was used to measure length by counting the number of spaces. ![]() About 2,500 years ago the Ancient Egyptians could be credited with making a very practical number line. One of the more important “inventions” for mathematics has been the number line. Simple tools have been used to help make giant leaps to understand or explain new ideas in science, mathematics, and technology. The number line: A powerful tool in the primary maths classroom ![]()
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