Lesson 1

1. Lesson 1

1.7. Explore 3

Mathematics 30-3 Module 6

Module 6: Measurement

This is a picture of a crankshaft.

iStockphoto/Thinkstock

The more precise a measurement is, the easier it is to accurately reproduce the measurement.

precision: the smallest measurement on the measuring device being used

Source: MathWorks 12 Student Book/Teacher Guide.

(Vancouver: Pacific Educational Press, 2011.)

Choosing the right device in measuring length is important. When marking the length of a football field, a device with a precision of 0.1 cm is not needed—a field that is off by millimetres is unlikely to affect the outcome of a game. When measuring the outside diameter of a crankshaft in an engine, a device with a precision of 0.01 cm or smaller should be used, because the crankshaft will need to fit tightly with other engine parts.

Did You Know?

This picture shows a jig used to cut the end of a board to a 45° angle.

This jig is used to cut the end of a board to a 45° angle.

When doing repetitive work, carpenters will often set up a jig. A jig is a good tool to use to cut the same measurement many times and ensure the same amount of accuracy. A jig is an invaluable tool, which you may be able to create yourself. For example, panel cutting jigs ensure that a panel is cut square to the bottom edge of the board. Circle cutting jigs allow you to cut perfect circles out of stock. Tapering jigs let you cut tapered legs on a table saw.

Self-Check 2

State the precision of each of the following measurements:

Measurement Tool	Measurement	Precision
Metric Ruler	23.6 cm	____ cm
Graduated Cylinder	73 mL	____ mL
Micrometre	6.91 mm	____ mm
Yardstick	31.6 in	____ in
Thermometer	25.7°C	____°C
Stopwatch	13.47 s	____ s

Answer

Remember, precision is the size of the smallest increment on the measuring device.