Minds On
Line time
Explore the following image.
As you explore the image, ask yourself these questions. You can record your thinking using a method of your choice.
- What do you notice and wonder?
- What could this be about?
- What information is it telling us? How can this be used?
A number line in the form of a timeline. The timeline starts with 6 am on the left and ends with 6 pm on the far right. On the number line, there are hourly intervals. From 6 am to 8 am, it is labelled shower, dressing, and breakfast. From 8 am to 9 am, it is labelled bus. School is labelled from 9 am to 3 pm. From 3 pm to 4 pm, it is labelled bus. From 4 pm to 5 pm, it is labelled homework. And 5 pm to 6 pm, it is labelled T.V.
Action
Representing time
Time is represented using seconds, minutes, and hours.
Explore these units of time by pressing on each tab.
Elapsed time describes how much time has passed between two times. Clocks and open number lines can be used to measure and/or calculate elapsed time.
Open number lines
An open number line is a line with arrows on either end and no numbers.
The following image displays an open number line.
An open number line can be used as a timeline to track events or a schedule.
It can also be used to track multiple steps and different units when calculating elapsed time.
It can be used to count forwards and backwards.
Elapsed time example
Let’s explore an example.
A baker starts to make a cake at 12:10 p.m. and finishes at 12:22 p.m. How much time does it take for the baker to make the cake?
Let’s try to find out the elapsed time together.
Before we begin, press ‘Hints’ to reveal some helpful tips about this word problem. Keep these in mind as we explore the example.
- an hour has not passed, as both times are still indicating 12 o’clock (12:10 and 12:22)
- the amount of time passed will be less than 60 minutes, as there are 60 minutes in one hour
To help us solve this problem, we can use a number line.
We will use the number line to count on or forward by 2, 5, or 10 minutes, or using a combination of these.
The open number line can start at 10 and contain numbers to 22. We can count by 5’s to get to 20, and then count by 1’s to get to 22.
There is a number line numbered from 10 to 22, from left to right. The section of the number line from 10 to 15 is highlighted and labelled 5. The next section on the number line, from 15 to 20, is also highlighted and labelled 10. The section from 20 to 21 is highlighted and labelled 11. The section from 21 to 22 is highlighted and labelled 12. The number line is showing that there are 12 minutes between 10 and 22.
5 + 5 + 1 + 1 = 12 minutes
12 minutes have passed from 12:10 p.m. and 12:22 p.m. So, it takes the baker 12 minutes to make the cake.
Your turn!
Using a number line or another strategy, determine the elapsed time for one of the following events:
|
Event |
Start time |
End time |
|---|---|---|
|
Event 1 |
5:20 p.m. |
5:55 p.m. |
|
Event 2 |
2:04 p.m. |
2:32 p.m. |
Record your ideas in a notebook or a method of your choice.
When you’re ready, press ‘Answers’ to reveal the elapsed time for the two events.
Possible student responses
|
Event |
Start time |
End time |
Elapsed time |
|---|---|---|---|
|
Event 1 |
5:20 p.m. |
5:55 p.m. |
35 minutes |
|
Event 2 |
2:04 p.m. |
2:32 p.m. |
28 minutes |
Mixing up the units of time
An open number line can also be used to calculate elapsed time using different units.
Let’s explore an example:
If a gardener takes a break from 12:36 p.m. until 1:15p.m., how would we calculate the elapsed time between the start and end of his break?
Let’s try to find out the elapsed time together.
Before we begin, press ‘Hint’ to reveal a question to consider about this word problem. Keep this in mind as we explore the example.
- Since the hour has changed from 12 to 1, does this indicate that the break was longer than an hour?
To find the elapsed time, we can use an open number line.
A number line will help us count on, or count forwards, to determine the elapsed time.
The following number line starts at 1:47 and ends at 2:06. The number line goes up by minutes.
A number line that starts at 1:47 and ends at 2:06. The number line goes up by minutes. The section from 1:47 to 1:50 is 3 minutes. From 1:50 to 1:55, it is 5 minutes. From 1:55 to 2:00, it is 5 minutes. From 2:00 to 2:05, it is 5 minutes. And from 2:05 to 2:06, it is labelled one minute.
On the number line, the minutes are recorded between each jump.
- We count forward from 1:47 to 1:50 by ones, and that equals 3 minutes.
- Next, we count from 1:50 to 2:05. We can count by 5’s, which equals 15 minutes.
- Then, we count from 2:05 to 2:06. We can count by 1’s, which equals 1 minute.
Finally, we add all the sections together:
3 minutes + 15 minutes + 1 minute
= 19 minutes
True or false?
Explore the following questions and determine if they are true or false.
If the question is false, think about what needs to be changed to make it true.
Task: Solar eclipse
Consider the following question:
A solar eclipse begins at 6:45 a.m. and ends at 8:25 a.m.
How long does the solar eclipse last?
Answer this question. Record your ideas in a notebook or a method of your choice.
When you’re ready, press ‘Answers’ to reveal a possible response to this question.
Possible student response
- I used the number line and counted 15 minutes from 6:45 a.m. to 7:00 a.m.
- Next, I noticed it was one whole hour from 7:00 a.m. to 8:00 a.m.
- Then, I counted 25 minutes from 8:00 a.m. to 8:25 a.m.
1 hour + 15 minutes + 25 minutes
= 1 hour and 40 minutes
The eclipse lasts 1 hour and 40 minutes.
A number line that starts at 6:00 and goes to 9:00. Each unit on the number line represents 15 minutes. The section from 6:45 to 7:00 is highlighted and labelled 15 minutes. The section from 7:00 through 8:00 is highlighted and labelled 1 hour. The section between 8:00 and 8:25 is highlighted and labelled 25 minutes.
Consolidation
Practice time!
An athlete is attending a summer training camp. The athlete goes to the camp from 7:30 a.m. to 8:00 p.m.
The athlete has many other activities during and after the day. These activities are listed in the following chart, but some of the times are missing! Help the athlete by filling in the missing details on their schedule.
You can complete this activity using the following fillable and printable Athlete Activity Chart. You can also complete this in your notebook, or use another method of your choice.
|
Activity |
Start time |
End time |
Elapsed time |
|---|---|---|---|
|
Morning yoga and mindfulness |
7:30 a.m. |
8:12 a.m. |
|
|
Lunch |
11:55 a.m. |
55 minutes |
|
|
Team meeting |
2:30 p.m. |
45 minutes |
|
|
Break |
3:06 p.m. |
3:33 p.m. |
|
|
Evening practice |
6:30 p.m. |
1 hour and 15 minutes |
Consider using the following analog clock or open number line to help you.
Press the 'Activity' button to access Athlete Activity Chart.
Think about your learning
Record your ideas to the following questions in a notebook or a method of your choice.
- How can a number line be used to calculate elapsed time?
- How are minutes and hours related? How does this relationship help you to solve for elapsed time?
Reflection
As you read through these descriptions, which sentence best describes how you are feeling about your understanding of this learning activity? Press the button that is beside this sentence.
I feel...
Now, record your ideas using a voice recorder, speech-to-text, or writing tool.
Press ‘Discover More’ to extend your skills.
Discover More
A teacher gets to school at 7:30 a.m. to set up the classroom, and class starts at 8:45 a.m. Determine the elapsed time from when the teacher arrives at school and when class starts.
Record your ideas in a notebook or a method of your choice.