Measuring Length

Section 7.1

Objectives

• Recognize and use appropriate units of length from the English and metric measuring systems • Convert units of length – Unit fractions within the same system – Unit fractions between systems – Moving the decimal point in the metric system • Perform operations on measurements

Objective 1: Recognize and use appropriate units of length from the English and metric measuring systems

Objective 1

• Unit of measure – name of a quantity that is used as a standard • English system • Metric system

Objective 2a: Convert units of length Unit fractions within the same system

Objective 2a

• Equivalent measurements – measures of same amount but using different units • Fraction with one unit as numerator and other as denominator is equivalent to 1 (Unit fraction) • Unit fraction converts measurement with one unit to measurement with another unit • Measurement x Unit fraction = Converted measurement • May need to multiply by more than 1 unit fraction to get to final units

Objective 2a

• To convert units of length – Multiply by unit fraction that has desired units in numerator and original units in denominator – Simplify

Objective 2b: Convert units of length Unit fractions between systems

Objective 2b

• Use system to system equivalents to write unit fraction • Same method as converting within same system

Objective 2c: Convert units of length Moving the decimal point in the metric system

Objective 2c

• Metric system based on powers of 10 • Shortcut for metric-to-metric conversions – Multiply or divide by powers of 10

Objective 2c

• Kilometer (km) = 1000 m • Hectometer (hm) = 100 m • Dekameter (dam) = 10 m • Meter (m) = 1 m • Decimeter (dm) = 0.1 meter • Centimeter (cm) = 0.01 meter • Millimeter (mm) = 0.001 meter

Objective 2c

• To convert units within the metric system – Move decimal point same number of places as number of unit changes

Objective 3: Perform operations on measurements

Objective 3

• To multiply or divide a measurement by a number – Multiply or divide numbers and write unit of measure • To add or subtract measurements – If units of measure are unlike, convert to like measures – Add or subtract numbers and write unit of measure