About this video
Sal reads a time from a number line that runs from 1:00 to 2:00. He first finds the hour, then counts tick marks (each one a minute) to find the minutes, and shows a faster way using the 5-minute tick marks. The time shown is 1:25.
You'll be able to
- find the hour on a time number line by seeing which two hours the point is between.
- count tick marks on a time number line to find the minutes.
- count by fives using the medium tick marks to read a time faster.
Key words
- number line
- A line with marks in order that we can use to show numbers, or here, times.
- timeline
- A number line that shows times in order.
- tick mark
- A small line on a number line; here each small one stands for one minute.
- minutes past
- How many minutes have gone by since the hour started.
Transcript
- [Instructor] We're told to look at the following number line. In this number line, we actually have times on it, so you could even call it a timeline. We're starting at one o'clock here. Then we go to 1:15, 1:30, 1:45, then two o'clock. And it says, what time is shown on the number line?
So, pause this video and see if you can figure that out. All right, so the hour I think is pretty straightforward. We are past one o'clock but we are before two o'clock. So, we know that the hour is going to be one something. It's not going to be two something 'cause we haven't gotten to two o'clock yet.
Now, what is the number of minutes after one o'clock? Well, we have a hint here. It's going to be between 15 and 30. And where would it be? Well, one way to tell is if you look at each of these tick marks, it looks like they represent a minute. Let's just count.
If we start at one, we go to 1:01, two, three, four, five, six, seven, eight, nine, 10, 11, 12, 13, 14, 15. Yep, it looks like each of these tick marks is a minute. So, we just have to figure out how many tick marks we are past 1:15. So, we can see that we can go from 15 to 16, 17, 18, 19, 20, 21, 22, 23, 24, 25.
So, we're 25 minutes past one o'clock. Another way you could have thought about it is each of these medium tick marks represent five minutes. And you can count, one, two, three, four, five. So, that's five, that's another five. So, this time right over here is going to be five plus five is 10, it's going to be 10 minutes past 1:15.
Well, 15 plus 10 is 25 again. So, the time shown on the number line 1:25.
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