Constant Speed
5 min
Teacher Prep
Setup
Required Preparation
Set up 4 paths as shown in the diagram, with a 1-meter warm-up zone and a 10-meter measuring zone. Mark the beginning of the warm-up zone, the start line, and the finish line.
Narrative
This Warm-up serves two purposes. The first purpose is to familiarize students with the protocol for the next activity, in which they will measure the time it takes someone to travel a distance at a constant speed. The second is to prompt students to begin thinking about the meaning of “constant speed.” Students observe a demonstration of the time-measurement process, predict how the speed of movement affects the measured time, and consider why it might be important for the person being timed to begin moving before the timer starts.
Launch
Tell students that you will perform an experiment that involves timing how long it takes someone to move the distance from the start line to the finish line. Select a student to be your partner.
Ask the student to stand at the warm-up mark of one of the paths prepared before class. Explain that the student has two main tasks:
- To move at a slow and steady speed toward the finish line
- To say “Start!” when they reach the start line so that you know when to start the stopwatch
Explain that when they reach the finish line you will stop the stopwatch and record the time, rounding it to the nearest second.
Before starting, stress the importance of the student moving at a constant speed while being timed. To encourage them to move slowly, consider asking the student to move as if they are balancing something on their head or carrying a full cup of water, trying not to spill it.
Demonstrate the experiment. Tell the class when the stopwatch is started and when it is stopped. Record and display the time for all to see. Give students 1–2 minutes to answer the questions.
Student Task
Your teacher will time how long it takes a student to move from the start line to the finish line of a path.
- How many seconds did it take the student to travel from start to finish?
- Suppose another student also moved along the same path but did it more quickly. How would the amount of time change?
- In the experiment, the student began moving from a warm-up mark that was before the start line. Why might it be important for the experiment?
Sample Response
- Answers vary.
- It would take less time to travel the given distance if the student moved more quickly.
- Sample responses:
- It allows the student to get used to moving slowly before the timer starts.
- It gives the student a chance to reach a constant speed before being timed.
Activity Synthesis (Teacher Notes)
First, invite a few students to share their predictions about the time it would take a faster mover to go from start to finish. Make sure that students see that it would take a shorter amount of time to move the same distance at a faster speed.
Then ask students to share why it might be important that the mover begins moving before the start line. Consider asking:
- “Suppose the mover started moving from the start line instead of from the warm-up mark. What can you say about the speed of the mover just as they were leaving the start line? How would that speed compare to their speed later on the path?”
- “What do you think ‘constant speed’ means?”
The key takeaway is that when an object moves at a constant speed, it doesn’t move faster or slower at any time. The initial 1-meter-long stretch, the warm-up zone, is there so the mover can accelerate to a constant speed before the timing begins.
Tell students that in the next activity they will do the experiment in small groups. When it is their turn to be the mover, they will need to move at a constant speed.
Standards
- 6.RP.3.b·Solve unit rate problems including those involving unit pricing and constant speed. <em>For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?</em>
- 6.RP.A.3.b·Solve unit rate problems including those involving unit pricing and constant speed. <span>For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?</span>
20 min
10 min
Knowledge Components
All skills for this lesson
No KCs tagged for this lesson
Constant Speed
5 min
Teacher Prep
Setup
Required Preparation
Set up 4 paths as shown in the diagram, with a 1-meter warm-up zone and a 10-meter measuring zone. Mark the beginning of the warm-up zone, the start line, and the finish line.
Narrative
This Warm-up serves two purposes. The first purpose is to familiarize students with the protocol for the next activity, in which they will measure the time it takes someone to travel a distance at a constant speed. The second is to prompt students to begin thinking about the meaning of “constant speed.” Students observe a demonstration of the time-measurement process, predict how the speed of movement affects the measured time, and consider why it might be important for the person being timed to begin moving before the timer starts.
Launch
Tell students that you will perform an experiment that involves timing how long it takes someone to move the distance from the start line to the finish line. Select a student to be your partner.
Ask the student to stand at the warm-up mark of one of the paths prepared before class. Explain that the student has two main tasks:
- To move at a slow and steady speed toward the finish line
- To say “Start!” when they reach the start line so that you know when to start the stopwatch
Explain that when they reach the finish line you will stop the stopwatch and record the time, rounding it to the nearest second.
Before starting, stress the importance of the student moving at a constant speed while being timed. To encourage them to move slowly, consider asking the student to move as if they are balancing something on their head or carrying a full cup of water, trying not to spill it.
Demonstrate the experiment. Tell the class when the stopwatch is started and when it is stopped. Record and display the time for all to see. Give students 1–2 minutes to answer the questions.
Student Task
Your teacher will time how long it takes a student to move from the start line to the finish line of a path.
- How many seconds did it take the student to travel from start to finish?
- Suppose another student also moved along the same path but did it more quickly. How would the amount of time change?
- In the experiment, the student began moving from a warm-up mark that was before the start line. Why might it be important for the experiment?
Sample Response
- Answers vary.
- It would take less time to travel the given distance if the student moved more quickly.
- Sample responses:
- It allows the student to get used to moving slowly before the timer starts.
- It gives the student a chance to reach a constant speed before being timed.
Activity Synthesis (Teacher Notes)
First, invite a few students to share their predictions about the time it would take a faster mover to go from start to finish. Make sure that students see that it would take a shorter amount of time to move the same distance at a faster speed.
Then ask students to share why it might be important that the mover begins moving before the start line. Consider asking:
- “Suppose the mover started moving from the start line instead of from the warm-up mark. What can you say about the speed of the mover just as they were leaving the start line? How would that speed compare to their speed later on the path?”
- “What do you think ‘constant speed’ means?”
The key takeaway is that when an object moves at a constant speed, it doesn’t move faster or slower at any time. The initial 1-meter-long stretch, the warm-up zone, is there so the mover can accelerate to a constant speed before the timing begins.
Tell students that in the next activity they will do the experiment in small groups. When it is their turn to be the mover, they will need to move at a constant speed.
Standards
- 6.RP.3.b·Solve unit rate problems including those involving unit pricing and constant speed. <em>For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?</em>
- 6.RP.A.3.b·Solve unit rate problems including those involving unit pricing and constant speed. <span>For example, if it took 7 hours to mow 4 lawns, then at that rate, how many lawns could be mowed in 35 hours? At what rate were lawns being mowed?</span>