Elapsed Time I can compute elapsed time to the minute.

Created by Stephanie Magnuson

Essential Questions

•1. How many hours are in one day? How many minutes are in one hour?

•2. What is elapsed time? What strategies can you use to determine elapsed time?

Let’s see what we already know about time?

Looking at the clock, do you

know...

What the big numbers

represent?What the big hand

represents?

What the small hand

represents?

How many hours are in 1 day?

How many minutes are in an hr?

What the red hand

represents?

What AM means?

What PM means?

See, you are an expert!

•Wow, you are amazing! It looks like you already know a lot about telling time. This will be easy for you!

•Today we are going to learn how to calculate how much time goes by at a given time.

•This is called Elapsed time.

Let’s practice using a clock!

Use your slates.

On your clock, show me how to split it into halves.

Now show me how to split it into quarters.

Now show me: 7:205:24 10:50 12:00

What if you had to add time?

Right now, it is ?. Show me on your clock what that looks like.Good! Now, use your clock to calculate what time it will be

in 20 minutes.

5

5

5

5 Remember: When you are counting

minutes, make sure you move the hour hand once you pass the

12.So... If you add 20 minutes to____, it

will be ______.

Now you try...Use your clock to help you

It is 12:10 now. What time will it be in 25 minutes?

It is 6:40 now. What time will it be in 20 minutes?

It is 9:00 now. What time will it be in 36 minutes?

It is 8:40 now. What time will it be in 15 minutes?

You got it! Now let’s move on.

12:35

7:00

8:55

9:36

So how do I calculate elapsed time?

Imagine that you are sitting in your desk waiting patiently for lunch. It is only 10:15 and lunch is at 11:30 but your stomach is growling and you are hungry. You need to figure out how long you have until lunch time. How do

YOU do it?

10:15 11:30

Let’s try it...Step 1: Count up to the hours

1 hour!

Step 2: Count up to the minutes

(From the 3 to the 6 is how many minutes?)

15 minutes!

(From the 10 to the 11 is how many hours?)

10:15 11:30

Last step: Add the hours and

minutes together

11:3010:15

Hours : Minutes

1 : 00

0 : 15+1 : 15

Can also be read as: 1 hour, 15 minutes

OR a quarter after 1

Let’s try another one

How long does it take to fly from Houston to Orlando?

Departure TimeHouston 8:00 am

Arrival TimeOrlando 11:10 am

8:00 11:10

Step 1: Count up to the hours

Step 2: Count up to the minutes

(From the 12 to 2 is how many minutes?)

(From 8 to 11 is how many hours?)3 hours!

10 minutes!

Step 3: Add them together3 : 000 : 10+3 : 10

3 hours and 10 minutes

What about this one...

Natalie and Maria left Sycamore at 2:16 pm. They walked for 14 minutes before arriving at Maria’s house. Then they went to Natalie’s house, which took them 18 minutes. What time did they arrive at Natalie’s house?

Step 1: Set up your clock

Step 2: Add up the minutes2 : 160 : 140 : 18+

2 : 48 minutes

They arrived at 2:48 PM

Let’s get a little tougher...

Uh Oh! There are only 60 minutes

in 1 hr. What do we do?

The Harris’s are driving to San Diego for the weekend. The clock shows what time they left.

The drive will take 6 hours and 30 minutes. What time should they expect to arrive?

Start time: 8 : 45 AMAdding the drive: 6 : 30

14 : 75

You got it! Regroup the 60 min..

- : 60

1

15 : 15

AM

Keep goin’

15 : 15Look at the clock, can we have

15 hours???No! Remember, the 1st 12

hours of the day are AM, and the 2nd 12 hours of the day

are PM. If we pass the 12, we move into the afternoon.

- 12 : 00

3 : 15 PM

The Harris’s should arrive in San Diego at 3 :15 PM.

Your turn!1. Sam’s soccer practice starts at 5:30 PM. It

usually runs about 1 hr, 15 minutes long. What time should he be finished?

2. Aidan went to Magic Mountain with his dad. They arrived at 9:00 AM. They rode lots of rides and ate lunch. They were there for 5 hours and

22 minutes. What time did they leave?3. Bryce and Jen went to a movie at 2:30 PM.

The movie was 2 hours long. Half way through, Jen went to the bathroom. What time did she

go?

5:30 + 1:15 = 6:45 PM

9:00 + 5:22 = 14:22 - 12 hrs = 2:22 PM

1/2 of 2= 1 hr. 2:30 + 1:00 = 3:30 PM

Closure

Use the clock below to create your own elapsed time word problem. When you are finished, you can switch boards with your shoulder partner

and solve their problem. Have fun!