# MATH

• WELCOME TO MATH!

Today we will cover the topic of 'Elapsed Time.'

Please look at the following times:
7:15
7:20
7:25
7:30
You can see that these times begin at 7:15 and then move five minutes around the clock until they stop at 7:30.
The amount of time between the beginning time and the ending time is called 'Elapsed Time.'
So, the elapsed time betwen 7:15 and 7:30 is fifteen minutes.

The top problem on the page shows two clocks which mark the time Gina leaves school (3:05) and the time she arrives home (3:25). You can count by fives (beginning at 3:05) to find out how long it takes Gina to get home (at 3:25).
Please use the clocks on page 290, and give it a try!

►Now let's try the second problem. In order to figure out the difference between Jim's recess time and his lunch time, we would have to travel completely around the clock a couple of times. That would be quite a lot of 'skip counting by 5s,' so instead we will first count by hours, and then we wlll count by fives for the difference in minutes.

So we begin at 10:20 and add one hour = 11:20

11:20 plus one hour = 12:20

Now we are at 12:20, but we are trying to get to 12:30.
If we add one more hour, we will go too far on the clock.

12:20 plus five minutes 12:25

12:25 plus five minutes = 12:30

Now we can add up the hours and the minutes to get the total elapsed time.

1 hour + 1 hour + 5 minutes + 5 minutes = 2 hours and 10 minutes
There are 2 hours, 10 minutes between Jim's recess and lunchtime.