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### Course: Middle school math (India) > Unit 1

Lesson 10: Week 10- Telling time (labeled clock)
- Concept of hour, minute, second
- Telling time (unlabeled clock)
- Time: Measurement questions on clocks
- Intro to data handling
- Data comprehension
- Picture graphs
- Display of data by picture diagrams
- Reading bar graphs: bikes
- Display of data using bar graphs

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# Telling time (unlabeled clock)

Sal tells time on unlabeled analog clocks. Created by Sal Khan.

## Want to join the conversation?

- Is it smarter idea to learn time on a digital watch before an analog watch that tells you the time?(7 votes)
- I agree. It is good to be able to tell time the harder way.(5 votes)

- why do we need A.M. and P.M.?(3 votes)
- We need AM and PM to calculate the days and hours. “AM” stands for the Latin phrase Ante Meridiem —which means “before noon”—and “PM” stands for Post Meridiem : “after noon.”" So if you think of it as AM means morning and PM means night.

Hope this helps!(2 votes)

- When we write time dose the mins come first(0 votes)
- The order is hours, minutes, and seconds. Usually just hours and minutes are used.(15 votes)

- where did 60 seconds in minute, 60 minutes in a hour, and 24 hours in a day come(2 votes)
- Ancient Babylonians. They used number base 60 (Sexagesimal).(4 votes)

- why is time different in different parts of the world shouldn't it just be the same?

It would be a lot less confusing.(2 votes)- Yes but say if you were in China and someone was in America. For example,6:00AM in America.

For some places at that time, the sun may be setting or just rising.

They also have different time zones so you could have an average like8:00AM --8:00PM and you could use as much as the daylight as possible.

As mentioned on http://www.timeanddate.com/time/time-zones.html, here's a more in-depth reason:

"Many towns and cities around the world used to set clocks based on observing the sun and the stars. This occurred prior to the late 19th century. Dawn and dusk occur at different times at different places because of the Earth’s rotation. However, time differences between distant locations were barely noticeable because of long travel times and the lack of long-distance communications. The expansion of transport and communications, as well as trade globalization, during the 19th century created a need for a more unified time-keeping system."(3 votes)

- does the second minute hand always move when the second hand counts 60 seconds because it doesnt look like it(1 vote)
- It sure does. The minute hand will move to the next minute after 60 seconds.

Example:

If the minute hand is on 1, it will be on minute 2 after the second hand counts 60 seconds.(4 votes)

- Is 13 in 24 hour time 1 AM?(1 vote)
- No it's 1 PM. It works very easily actually when you think about it. Hour 1 in military time (24 hour time I suppose you could say) is 1 AM, the first hour of the day. So 13 hours threw the day would get you to 1 PM. If you can subtract 12 from the number it is in the PM if not it's in the AM. The actual time is minus 12 then just add PM. So again 13-12=xPM x being the number with PM on the end since you can subtract a 12 from 13.(3 votes)

- if it takes Earth 24 hours to spin all the way around (360 degrees) than how many hours, days, weeks, months, or years does it take for Jupiter to completely turn around?(1 vote)
- Believe it or not, Jupiter actually spins really fast, fast enough that 1 complete rotational period is 10 hours! These speeds also contributes to the constant storms on Jupiter, as well as the Giant Red Spot.(3 votes)

- How we say the time differs in languages. I speak three languages and others say ''five without 10''. So these videos are teaching the time in english right?(1 vote)
- This site works in English, primarily, but it has some translate options as well(2 votes)

- what if it was 100 minutes past the hour?(1 vote)
- Well 60 minutes are in an hour. If you think about it you can see that there is a group of 60 in 100. Next we should figure out how many "extra" minutes are there so 100-60=40 so 100 minutes is 1 hour and 40 minutes so if we at1:00P.M. adding 100 minutes gets us to2:40P.M. Hope this helps.(2 votes)

## Video transcript

We're asked, what time is it? So first, we want to look at the
hour hand, which is the shorter hand, and see where
it is pointing. So this right over
here would have been 12 o'clock, 1 o'clock, 2
o'clock, 3 o'clock, 4 o'clock. And it looks like it's a
little bit past 4 o'clock. So we are in the fourth hour. So the hour is 4. And then we have to
think about the minutes. The minutes are the longer hand,
and every one of these lines represent 5 minutes. We start here. This is 0 minutes past the hour,
then 5 minutes past the hour, then 10 minutes past the hour. So the time is-- the minutes are
10, 10 minutes past the hour, and the hour is 4, or it's 4:10. Let's do a few more. What time is it? So first, we want to
look at the hour hand. That's the shorter
hand right over here. It's at-- let's see. This is 12, 1, 2,
3, 4, 5, 6, 7, 8, 9. And it's between 9 and 10. It's just past 9. So it's still in the ninth hour. It hasn't gotten to
the 10th hour yet. The ninth hour's from starting
with 9 all the way until it's right almost before
it gets to 10, and then it gets
to the 10th hour. So the hour is 9, and
then we want the minutes. Well, we can just
count from 0 starting at the top of the clock. So 0, 5, 10, 15, 20, 25, 30. It's 9:30. And that also might
make sense to you, because we know there are
60 minutes in an hour. And this is exactly
halfway around the clock. And so half of 60 is 30. Let's do one more. What time is it? So let's count. This is 12, 1-- actually,
we can even count backwards. We can go 12, 11, 10. So right now we're
in the 10th hour. The hour hand has passed 10,
but it hasn't gotten to 11 yet. So we are in the 10th hour. And how many minutes
past the hour are we? So this would be 0, 5, 10,
15, 20 minutes past the hour. That's where the longer
hand is pointing. It is 10:20.