To understand what a slide rule is, you need to know what a scale is. A scale of measurement is a level of measurement which in turn is an expression. Scale is used not just in Mathematics but also in psychology where it is referred to as the theory of scale types. Likewise a slide rule affords a diverse range of scale types where the expressions appear in a linear or circular form with standardized markings. A scale in simple words is a range of measurement. There is a proportion by which its order is arranged. A slide rule is known as a slipstick in the colloquial sense which is used for multiplications and divisions and also for roots, logarithms and trigonometry. It can be referred to as a mechanical analogue device.
For beginners slide rules are not found to be intuitive but difficult calculations can be performed using them. Before there were calculators mathematicians used slide rules. An Episcopalian Mathematician, William Oughtred invented what are known as circular and rectangular slide rules. It was used as a calculating tool and John Napier made it possible to calculate by the invention of logarithms. While students who are introduced to slide rules tend to find it overwhelming with the nature of terms and calculations needed to be performed using it, its convenience must be explained. By pointing out just how convenient slide rules made calculations before digital computers students will understand the relevance of this system of scales.
The difficulties encountered in this topic are usually the need to remember how to use the scale. Understanding logarithms is also found difficult but by explaining the need for logarithms the subject becomes more pleasant. Teachers need to explain the convenience that it affords us otherwise it will appear to be outlandish to learners. This is the challenge that a tutor or a teacher may face when introducing new subjects. There are two levels of the same challenge where a subject has to be introduced as a friendly customer and at the next level practice becomes the key to retain the principles behind its necessity. Do you know that several inventors improved upon William Oughtred’s first slide rule? It may interest the learner to know that the first slide rule was made by inscribing logarithms on wood or ivory. By pointing out such details about the historical background of the subject slide rules can be studied with greater intensity as a natural outcome of inspired online tutoring.