Chapter 10 Lesson 4
Count Time With Hours
Military Time
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We did 1 kind of time, but
there is another one we use alot.
Military Time
Military time? What's that?
You played with G.I. Joe's
when you were a kid, didn't you?
Uhhh, I have 8 of them
with tents and everything.
Oh, I forgot. You still are a kid.
So, you know what the military is.
Tomorrow we're having an
invasion at my friend's backyard.
Wanna come? It's a blast.
I'll pass, but it sounds like fun.
Ok, I'll here's a problem for it.
The invasion starts at 10:00 and
lasts 3 hours. When does it end?
Wow. I could conquer a
few countries in that time.
Here, I'll solve it for you.
Start
How long
10:00
+ 3:00
hours
13:00
end time
clock
I get that you added it,
but what time is 13 o'clock?
Start
How long
10:00
+ 3:00
hours
13:00
end time
clock
That's military time.
Their clock looks different.
Here's how you write it.
13 00
hrs
That's pretty crazy. 13 hours?
*There are other ways to write it.
13 00
hrs
Unless you're in the military
or work for the airlines.
13 00
hrs
I meant crazy in a nice way.
A very, very nice way.
13 00
hrs
A very, very very nice way. It's
a different way to write time.
I'll show you on a clock.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
Ok, that's the clock we use.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
23 24 13
14
22
15
21
16
20
19 18 17
Wow. That's really different.
It's got 13 to 24 on it.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
23 24 13
14
22
15
21
16
20
19 18 17
Exactly. I'll make a problem.
9 00 hrs - 14 00 hrs
They say 9 100 hours and
14 100 hours. How long is it?
9 00 hrs - 14 00 hrs
Oooh, that is really easy.
I even know the answer.
9 00 hrs - 14 00 hrs
5 hrs
Just subtract 14 - 9 is 5 hours.
I can't believe it. It's easy!
I thought you'd like that.
I'll make another like it.
Start
?
10 hours
End
20 00
A ski pass lasts 10 hours. It's over
at 20 hours. When does it start?
hrs
Start
?
10 hours
End
20 00 hrs
I could seriously ski 10 hours.
Ok, just subtract it out.
Start
10 hours
10 00 hrs
End
20 00 hrs
I'd start skiing
at 10 in the morning.
Start
10 hours
10 00 hrs
End
20 00 hrs
Yeah, but what time is 20 hours?
Start
10 hours
10 00 hrs
End
20 00 hrs
20 hours is 8 o'clock at night.
Start
10 hours
10 00 hrs
End
20 00 hrs
How did you figure that out?
20 00 - 12 00 = 8 00
I think you subtract 12.
I think you're right.
I'll make another problem.
Start
7:00 hrs
8 hours
End
?
hrs
Your dad works 8 hours starting
at 7:00. What time does he finish?
Start
8 hours
7:00 hrs
End
?
My dad gets up at 7,
but I know the answer.
hrs
Start
7:00 hrs
8 hours
End
15 00 hrs
My story problem dad works
until 15 hours. Just add 7 + 8.
Start
7:00 hrs
8 hours
End
15 00 hrs
What's the other time for 15:00?
15 00 - 12 00 = 3 00
Subtract 12 makes 3
in the afternoon.
So, what do you
think about military time?
Military Time
Why don't we use it all the time?
Good question. Probably
it's the habit of most people.
It makes it alot easier
than counting over 12.
Maybe I should join the military.
Your dad would sign the
papers if he could. Just kidding.
Oh, no. He thinks the army
would be a good thing for me.
My mom isn't so sure.
Tough choice. Whatever you
choose, it will change your life.
Qs
12
11
1
2
10
3
9
4
8
7
6
5
How is military time different?
12
11
1
24 13
23
2
10
14
22
15 3
9 21
16 4
20
8
17
19
18
5
7
6
The clock has 24 hours
instead of 12.
3:00 pm
How do you change
regular to military time?
3:00 + 12 = 15:00
Add 12
3 o'clock + 12 makes 15 hours.
13 00
How do you change
military to regular time?
13:00 - 12 = 1:00
Subtract 12
Subtract 12 to get regular time.
Chapter 10 Lesson 4a
Count Time With Hours
How to tell mornings from
afternoons in regular time.
You know how it talks about
morning and afternoon time?
Sure, it is what it is.
I try to live in the afternoon.
Morning isn't so great.
Well, there's another way to
say morning and afternoon.
I'll write them on the board.
AM
PM
What does AM and PM mean?
AM
PM
I'll show you with the clocks.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
AM
AM starts at midnight and
lasts all the way to noon.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
AM
How do I remember AM?
AM
All Morning
I named it All Morning for AM.
Then, what's the other one?
Afternoon
PM
23 24 13
14
22
15
21
16
20
19 18 17
PM is after noon and it lasts
the evening until midnight.
Afternoon
PM
23 24 13
14
22
15
21
16
20
19 18 17
PM? It's kind of confusing.
PM
Past Morning
I named it Past Morning
because it's after morning.
How about the army guys?
AM
PM
Upto 12:00 noon
13:00 to 24:00
They're AM is the same,
but they count 13 to 24.
AM
PM
Upto 12:00 noon
13:00 to 24:00
That makes alot sense.
Start
How long
10:00
+ 3:00
hours
13 00
end time
clock
So army guys would say
13 hours and know it was 1:00.
Start
How long
10:00
+ 3:00
hours
13 00
end time
clock
I can change that back.
13 00 - 12 00 = 1 00
Just subtract 12
to get back to AM/PM time.
13 00 - 12 00 = 1 00
And that's what we'll practice.
15 00
What time is 15 hundred
hours in AM/PM?
15 00
Oh, just like they do
in the movies. Subtract it.
15 00 - 12 00 = 3 00
You subtract 12 to get AM/PM.
That's pretty easy to remember.
21 00
Last one. Change to AM/PM.
21 00
Oooh, I have to remember this.
21 00 - 12 00 = 9 00
8 + 1 more makes 9 what?
21 00 - 12 00 = 9 00
What do you mean, 9 what?
21 00 - 12 00 = 9 00
Is 9:00 AM or PM?
21 00 - 12 00 = 9 00
Oh, I get what you're saying.
That's 9:00 PM.
Right. 21 hours is the
same time as 9 o'clock PM.
One last thing to talk about.
12 am
Is 12 am noon or midnight?
12 am
How am I supposed to know that?
12 am
Well, follow the clock.
You know 11 am is morning.
12 am
I guess that means 12 follows 11.
12 am is noon.
Right. 11 am
means 12 am is noon.
12 am is noon.
What about 12 pm?
It's midnight.
So, 12 pm is midnight
and starting the next day.
12 pm: midnight
I didn't know time
was so complicated.
And we haven't even
started counting minutes.
Qs
AM
PM
What do AM and PM mean?
AM
PM
All Morning
Past Morning
Morning is from midnight to noon.
PM is afternoon and evening.
AM
PM
How does military time use AM/PM?
AM
PM
Upto 12:00
13:00 to 24:00
AM counts upto 12:00.
PM counts 13 to 24 o'clock.
Chapter 10 Lesson 4
Count Time With Hours
Short Lesson
Military Time/Regular Time
Military Time
Instead of counting hours
in 12s it counts it in 24s.
It does not start over
at noon. It counts upto 24.
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
It has the same times
with military time.
How is the afternoon different?
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
23 24 13
14
22
15
21
16
20
19 18 17
It doesn't start over at 12.
It keeps on counting upto 24.
We'll make a problem for it.
Start at 11:00 in the morning and
add 3 hours. What's the end time?
How is this different from
the 1st time we counted it?
11:00
+ 3:00
Start
14 00
end time
How long
14 00 is military time.
It's the same thing as 2:00 PM.
Think about what it means.
14 00
is
2:00
14 00 hours is the same
as 2:00 in our time.
How do you change it back?
14 00 - 12 00 = 2 00
Subtract 12 to get our time.
We'll make a problem for it.
9:00 - 14:00
You start school at 9:00 and
leave at 14:00. How long is it?
Use it to find elapsed time.
9:00 - 14:00
5 hours
Subtract 14 - 9 is 5 hours.
It uses the same ideas
as start and end time.
Morning Afternoon
So far, we've talked about
morning and afternoon times.
There is another way to write it.
9 am
9 pm
Here are 2 times.
They both have 9, but they
are very different. Why is that?
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
9 am means in the morning.
When is 9 o'clock pm?
Morning
11 12 1
2
10
3
9
4
8
7 6 5
Afternoon
11 12 1
2
10
3
9
4
8
7 6 5
Same time, but it's in the evening.
What does AM and PM do?
AM
PM
AM: midnight and ends at noon.
PM: afternoon and evening
We have a way to remember it.
AM
PM
All Morning
Past Morning
Think of All Morning
and what's Past Morning.
How does it use military time?
AM
PM
Upto 12:00 noon
13:00 to 24:00
AM is the same,
but PM counts 13 to 24.
So, how do you change
military time to AM?PM time?
15 00
You know how 15 hundred
hours is in the afternoon.
How do you write it with PM?
15 00 - 12 00 = 3 00 pm
Change it by subtracting 12.
We'll make a few problems.
16 00
What time is 16 hundred
hours in AM/PM?
16 00 - 12 00 = 4:00 pm
Subtract 12 to get 4 PM.
We'll make 1 more problem.
10:00 pm
Change 10 pm to military time.
How do you change it that way?
10:00 + 12 = 22 00
hours
Add 12
Add 12 to find military time.
We'll go over this again.
5:00
What shows a time
happens in the morning?
5 am
AM means the
time is in the morning.
How can you remember AM?
AM
All Morning
Think that AM is all morning.
(Morning is from midnight to noon.)
5:00
What shows a time
happens in the afternoon?
5 PM
5 pm is after noon.
How can you remember PM?
PM
Past Morning
PM is after or past morning.
PM is afternoon and evening.
It ends at midnight.
Qs
How is military time
different from regular time?
12
11
1
24 13
23
2
10
14
22
15 3
9 21
16 4
20
8
17
19
18
5
7
6
The clock has 24 hours
instead of 12.
5:00 pm
How does military time
find pm time?
5 + 12 = 17 00
Add 12 for military time.
Military time counts hours upto 24.
Chapter 10 Lesson 4
Count Time With Hours
Practice #1
Military Time/Regular Time
3:00
How do you change
regular to military time?
3:00 + 12 = 15:00
Add 12
3 o'clock + 12 makes 15 hours.
1:00 am
1:00 pm
What do am and pm mean?
(Use our definitions.)
1:00 am
1:00 pm
AM is all morning.
(Midnight to noon.)
PM is past morning.
(Noon to midnight.)
Problems
5:00 in the afternoon
What's the military time for 5 pm?
5:00 + 12 = 17:00 hrs
Add 12 for military time.
It's 17 hundred hours.
9:00 at night
What time is 9 at
night in military time?
9 + 12 = 21:00
Add 12 for military time.
9 at night is 21 hours.
13:00
How do you change military
hours back to regular time?
13:00 hrs - 12 = 1:00
Subtract 12
Change military time to
AM/PM by subtracting 12.
20:00
military
What time is this in regular time?
20:00 - 12 = 8:00
Subtract 12
Subtract 12 is 8:00 pm.
Your jet lands at 10 am. Is that
in the morning or evening?
10 am
10 am is in the morning.
14:00
hrs
What time is 14:00 hrs in am/pm?
14:00 hrs is 2 pm
From 12:00 to 24:00 is pm.
Chapter 10 Lesson 4
Count Time With Hours
Practice #2
Military Time/Regular Time
3:00
How do you change
regular to military time?
3:00 + 12 = 15:00
Add 12
3 o'clock + 12 makes 15 hours.
1:00 am
1:00 pm
What do am and pm mean?
(Use our definitions.)
1:00 am
1:00 pm
AM is all morning.
(Midnight to noon.)
PM is past morning.
(Noon to midnight.)
Problems
4:00 in the afternoon
What's the military time for 4 pm?
4:00 + 12 = 16:00 hrs
Add 12 for military time.
Say it 16 hundred hours.
10:00 at night
What time is 10 at
night in military time?
10 + 12 = 22:00
hrs
Add 12 for military time.
10 at night is 22 hours.
14:00
How do you change military
hours back to regular time?
14:00 hrs - 12 = 2:00
Subtract 12
Change military time to
AM/PM by subtracting 12.
11:00
military
What time is 11 in regular time?
11:00
am
Same time, but now it's am.
You get up at 2 am. Is that
in the morning or evening?
2 am
2 am is in the morning.
15:00
hrs
What time is 15:00 hrs in am/pm?
15:00 hrs is 3 pm
From 12:00 to 24:00 is pm.
Chapter 10 Lesson 4
Count Time With Hours
Performance #1
Military Time/Regular Time
7:00 am
9:00 pm
Change to military time.
7:00 am
7:00
hrs
9:00 pm
21:00
hrs
7:00 pm
1:00 pm
What is each military time?
7:00 pm
19:00
hrs
1:00 pm
13:00
hrs
10:00 pm
12:00 pm
Change to military.
10:00 pm
22:00
hrs
12:00 pm
24:00
hrs
military
7:00
hrs
20:00 hrs
Change to regular time.
7:00 hrs
7:00 am
20:00 hrs
8:00 pm
military
14:00
hrs
21:00 hrs
Find regular time.
14:00 hrs
2:00 pm
21:00 hrs
9:00 pm
military
15:00
hrs
6:00 hrs
Change to regular.
15:00 hrs
3:00 pm
6:00 hrs
6:00 am
Chapter 10 Lesson 4
Count Time With Hours
Performance #2
Military Time/Regular Time
6:00 am
1:00 pm
Change to military time.
6:00 am
6 00
hrs
1:00 pm
13 00
hrs
5:00 pm
2:00 pm
What is each military time?
5:00 pm
17 00
hrs
2:00 pm
14 00
hrs
8:00 pm
6:00 pm
Change to military.
8:00 pm
20 00
hrs
6:00 pm
18 00
hrs
military
5 00
hrs
18 00 hrs
Change to regular time.
5 00 hrs
5:00 am
18 00 hrs
6:00 pm
military
13 00
hrs
24 00 hrs
Find regular time.
13 00 hrs
1:00 pm
24 00 hrs
12:00 am
military
12 00
hrs
4 00 hrs
Change to regular.
12 00 hrs
12:00 pm
4 00 hrs
4 00 am