Video Solutions to help Grade 6 students learn how to use the formula distance = rate • time.

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Common Core For Grade 6

Lesson 22 Student Outcomes

• Students decontextualize a given speed situation, representing symbolically the quantities involved with the formula distance = rate • time.

Lesson 22 Summary

Distance, rate, and time are related by the formula distance = rate • time.

Knowing any two of the values allows the calculation of the third.

If something is moving at a constant rate of speed for a certain amount of time, it is possible to find how far it went by multiplying those two values. In mathematical language, we say Distance = Rate • Time

Lesson 22 Classwork

Opening Exercise

• How many seconds are in minute?

• Can you verbalize this relationship?

• Represent the relationship in two ways.

Exercise 1

Walker: Substitute the walkers' distance and time into the equation and solve for the rate of speed.

Distance = Rate • Time

Hint: Consider the units that you want to end up with... If you want to end up with the rate ( ) then divide the distance (feet) by time (seconds).

Runner: Substitute the runner’s time and distance into the equation to find their rate of speed.

Distance = Rate • Time

Exercise 2

Part 1: Chris Johnson ran the 40 yard dash in 4.24 seconds. What is the rate of speed? Round any answer to the nearest hundredth of a second.

Distance = Rate • Time

Part 2: In Lesson 21, we converted units of measure using unit rates. If the runner could keep up this speed at a constant rate, how many yards would he run in an hour? This problem can be solved by breaking it down into two steps. Work with a partner, and make a record of your calculations.

a. How many yards would he run in one minute?

b. How many yards would he run in one hour?

• We completed that problem in two separate steps, but it is possible to complete this same problem in one step. We can multiply the yards per second by the seconds per minute, then by the minutes per hour.

Cross out any units that are in both the numerator and denominator in the expression because these cancel out each other.

Part 3: How many miles did the runner travel in that hour? Round your response to the nearest tenth.

Example 1

I drove my car on cruise control at 65 miles per hour for 3 hours without stopping. How far did I go?

d = r • t

Example 2

On the road trip, the speed limit changed to miles per hour in a construction zone. Traffic moved along at a constant rate (50 mph), and it took me minutes (0.25 hours) to get through the zone. What was the distance of the construction zone? (Round your response to the nearest hundredth of a mile).

2. A Salt March Harvest Mouse ran a centimeter straight course race in seconds. How fast did it run?