📊Math G3 L7.3 🤔Explore A - Elapsed Time on a Number Line

Part 1

What do you know?

• You leave for soccer at 5:00
• You can play until 6:30

What can you do?

• Determine how far it is from 5:00 to 6:30.

What is being asked?

• How long you can play.

This problem shows elapsed time.  Elapsed time is the amount of time that has passed between two set times.  Elapsed time is the duration of an event.  Both of these definitions show elapsed time.

Part 2

Elapsed time problems require three different components or pieces to solve:  

• the start time
• the time elapsed
• the end time

When a problem involving elapsed time is solved, the three components will have been determined or identified.

Part 3

Let's determine the three components.

What is the start time?

• 5:00

What is the elapsed time?

• we don't know yet

What is the end time?

• 6:30

Let's find the elapsed time.

We will use a number line.

Begin with an open number line.

Mark 5:00 and 6:30 on the number line.

Next, determine how far from 5:00 to 6:30.  

The total time is 1 hour and 30 minutes. 

Or 1 hour (which is 60 minutes) and 30 minutes.  This makes 90 minutes.

Or 1 hour and 30 minutes (1/2 hour).  This makes 1 and 1/2 hours.