What is a rule?
Rules are simple pieces of equipment. They can be used to measure straight lines on flat surfaces and as an aid when drawing, cutting or scoring straight lines on materials.
They can be made from various materials and may be flexible or rigid. There are many different lengths, widths, shapes and styles of rule.
Rules are used frequently in engineering, architecture, geometry and technical drawing. Also, they're commonly used for things such as measuring fabric lengths, design, DIY, paper crafts, and maths homework.
A ruler or a rule?
A rule may sometimes be called a ruler, and the terms rule and ruler are often used interchangeably. Generally a rule and a ruler are distinguished as: a rule, usually, measures straight from its edge; a ruler starts its measurement a little way in from the edge.
Rulers are common stationery items, often found in schools and children's pencil cases. They are usually made from wood or plastic and are generally 150mm (6") or 300mm (12") long.
They are often marked on one face, on either edge, with measurement gradations. Some opaque rulers are marked on both faces. The measurements are usually marked in centimetres, inches, or both, and then subdivided into millimetres or fractions of inches.
Rules are pieces of measuring equipment which are very similar to rulers, but they will usually have been more accurately calibrated. They can also be made from wood or plastic, as well as steel or aluminium.
They come in a larger variety of lengths and forms and often have measuring marks for centimetres and inches. There are sometimes other marks on rules, such as scale measurements, half millimetres or masonry bricklaying marks.
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