Arithmetic Grade Six

Lesson One Hundred Seventy: Distance


You can measure speed in any unit of length and time. For instance, all of the following are common units used in the measurement of speed: 


	miles per hour			centimeters per second

	kilometers per minute		meters per minute

	millimeters per day		inches per year
You might not think that anything could be measured in inches per year, but think about the growth of a tree or the movement of a glacier.

It's important to report your units along with your numbers when performing calculations involving distance, speed, and time. Here are some examples: 


	FIND THE DISTANCE COVERED:
	  TIME: 2 hours
	  SPEED: 50 kilometers per hour
	  DISTANCE (answer): 50 kilometers per hour * 2 hours = 100 kilometers

	FIND THE SPEED:
	  DISTANCE: 100 miles
	  TIME: 4 hours
	  SPEED (answer): 100 miles ÷ 4 hours = 25 miles per hour

	FIND THE TIME:
	  DISTANCE: 100 miles
	  SPEED: 50 miles per hour
	  TIME (answer): 100 miles ÷ 50 miles per hour = 2 hours

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