Page 498 - Canadian BC Science 9

480 MHR • Science Skill 7
Instant Practice—Estimating and Measuring
Imagine that all rulers within the school have vanished. The only measurement tool that you now have is a toothpick.
1. Estimate the length and width of your
textbook in toothpick units. Compare your estimates with your partner’s estimates.
2. Measure the length and width of your textbook with your toothpick. How close was your estimate to the actual measurement?
3. Estimate the length and width of your desk in toothpick units. Compare your estimates with your partner’s estimates.
4. Measure the length and width of your desk with your toothpick. How close was your estimate to the actual measurement?
5. If you had a much larger area to measure, such as the floor of your classroom, what could you use instead of toothpicks to measure? (Be creative!)
6. What is your estimate of the number of units you chose in (question 5) for the width of your classroom?
Measuring Volume
The volume of an object is the amount of space that the object occupies. There are several ways of measuring volume, depending on the kind of object you want to measure. A cubic metre is the space occupied by a 1 m 􏰁 1 m 􏰁 1 m cube. This unit of volume is used to measure large quantities, such as the volume of concrete in a building. In this course, you are more likely to use cubic centimetres (cm3) or cubic millimetres (mm3) to record the volume of an object.
You can calculate the volume of a cube by multiplying its sides. For example,
volume 􏰀 1 cm 􏰁 1 cm 􏰁 1 cm 􏰀 1 cm3.
You can calculate the volume of a rectangular solid if you know its length, width, and height.
volume 􏰀 length 􏰁 width 􏰁 height
If all the sides are measured in millimetres (mm), the volume will be in cubic millimetres (mm3). If all the sides are measured in centimetres (cm), the volume will be in cubic centimetres (cm3). The units for measuring the volume of a solid are called cubic units.