About this video
This video measures lengths to the nearest quarter unit with a ruler. Each whole unit is split into four equal sections, so a sunflower that reaches one section past 5 is 5 1/4 feet tall, and a pencil that reaches three sections past 2 is 2 3/4 inches long.
You'll be able to
- line up an object with the start of a ruler.
- read a length to the nearest 1/4 unit by counting equal sections between whole numbers.
- find which object matches a length like 2 3/4 inches.
Key words
- ruler
- A tool for measuring length, marked with whole units and smaller sections.
- quarter (1/4)
- One of four equal parts of a whole.
- hash marks
- The small lines on a ruler that split each unit into equal sections.
- mixed number
- A whole number and a fraction together, like 5 1/4.
Transcript
- [Instructor] We are asked what is the height of the sunflower? So pause this video and think about it. All right, so let's see. The bottom of the sunflower is right aligned with the bottom of the ruler, so there ruler's in the right place. And let's see, the sunflower goes all the way up to this point right over here.
So this is one, two, three, four, five, and then a little bit more. So we're going to get into a fraction. So what is this extra amount? So if we can see the space between five and six is divided into four equal sections. So we have, one, two, three, four. Or we could see it here.
They've divided it with these little hash marks into one, two, three, four equal sections. And this goes one of those four equal sections towards six, so this is 5 1/4 feet. That's how tall the sunflower is. All right, let's do another example. So here we are told, or we are asked, which pencil measures 2 3/4 of an inch?
So pause this video and try to think about it. All right, so we go one inch, two inches, and then we have to think about how far between two and three is 3/4? So to think about 3/4, we have to divide the part, or the part of this ruler, between two and three into four equal sections.
So let's see. If I were to just split it like this, that's two equal sections. So if I were to take each of those two equals sections and then split them, now that's four equal sections. Notice one, two, three, four equal sections. So when we're thinking about 3/4, we wanna go three of those four equal sections.
One, two, three. And so you can see right over here, that is 2 3/4. This is 2 3/4 right over here. And that is pencil A.
Video © Khan Academy, used under CC BY-NC-SA. Watch on Khan Academy. Puzzicle is not affiliated with Khan Academy.