If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains ***.kastatic.org** and ***.kasandbox.org** are unblocked.

Main content

Current time:0:00Total duration:6:56

CCSS.Math:

the base unit for distance in the metric system is the meter and to get a sense of how long a meter is the average human being is between 1.5 and 2 meters tall so 1.5 meters would be a not so tall person but 2 meters would be quite tall in fact if you're 2 meters tall or above 2 meters tall you might want to consider basketball so for example in this drawing right over here by Leonardo da Vinci a meter if this is an average-sized male a meter might be about a meter might be about it would be more than halfway across his wingspan so it might be about that much and obviously I am just roughly drawing this just to give you a sense of how far a meter might be and I just wrote a lowercase M here as really just a short way of writing meter so you can imagine that the the smaller things that you might want to measure with it with the meter are things like a human being a human beings height or human beings wingspan if you wanted to say well what are some of the larger things that you would want to measure with a meter you might imagine something like the height of a skyscraper so this right over here is the Empire State Building once at one time the tallest building in the world now just a tall building in the world and this is 443 meters tall 443 meters tall so this is starting to be kind of on the larger scale of things that you would want to measure with a meter now you're probably asking well what happens if I want to measure things that are even larger than that well the metric system provides us prefixes to essentially say multiples of meters and the one that's typically the the unit of distance that is larger than the meter that is most typically used is the kilometer so the kilometer I've heard a few people say kilometres with kilometer I'll pronounce it kilometer which is equivalent to 1000 1000 meters and so when you're thinking about kilometers this is thinking about the distance within a city this would be even the distance from one city to another city even the the radius of the planet is often measured in kilometers often in kilometers and to once again get a sense of that if you get a sense of that this right over here is a map of New York City and right over here they give us the scale this distance right over here is five is five kilometers so five kilometers just to give us a sense of things and they wrote km for short so 5 km 5 km this lowercase K lowercase M is the shorthand for kilometers this would be equal to well if one kilometer is 1,000 meters five kilometers is going to be five times as many it's going to be five thousand five thousand meters is this distance right over here if we were to try to imagine one kilometer it'd be one-fifth of that so one kilometer on this map might look something might look something like that now there's other units in the metric system that allow us to describe distances less than a kilometer but more than a meter but they're not as typically used but I'll list them here just to see just so that you see that they exist you have the hecto meter or hectometer it's so infrequently used that i really haven't heard a lot of people say it which is equal to 100 meters and you have the DECA meter or deck a meter and I actually think it's deco meter decameter deco meter which is 10 meters so I'm going to write these in orange because they're not that frequently used for example no one would ever say or it's not typical to hear someone say that the Empire State Building is 4.43 hectometer z-- or for them to say that this is forty four point three decameters they would typically say that this is 443 meters now you're probably saying okay well this is fine I'm able to using these prefixes on the meter I'm able to describe distances that are larger than a meter that are multiples of of tens of the meter or multiple 100 multiple of thousand of the meter but what if I want to go smaller well the metric system has units for that and if we go just one tenth of a meter this is not used as typically but I'll write it here the decimeter the decimeter is 1/10 of a meter or another way of saying it is one meter is equal to 10 decimeters lowercase DM for short once again this is not so typically used but if we go one scale even below that we get to the centimeter which is a heavily used unit we get to the centimeter centimeter and here the prefix centi means one hundredth so this is one hundredth of a meter one hundredth of a meter another way of thinking about it one meter is equal to 100 centimeters and if you want to imagine the scale of a centimeter you could imagine this frog right over here on this person's hand might be several centimeters long so a centimeter on this drawing might be around that distance now if you want to measure things even smaller than that we have another fairly common unit and that is the millimeter that is the millimeter and the prefix milli here refers to one thousandth so it's one thousandth of a meter or another way of thinking about it is one meter one meter is equal to 1000 1000 millimeter actually right let me just write em for short just we get used to also seeing it that way one meter is equal to 1000 1000 millimeters and if you wanted to imagine how long or how far a millimeter is you could go down the scale of things that are smaller than a centimeter so these ants for example might be 3 or 4 millimeters long so a millimeter and this drawing right over here might be might be something like that the important thing to realize is just or just to conceptualize as well you might want to use different units depending on the scale that you're measuring and it's also useful to just realize what these typical prefixes refer to because we're seeing it used in distance here they're all based on the base unit of distance but in other when we're measuring volume or we're measuring other things in the metric system these same you the same prefixes also show up so you see here when we're measuring distance kilo refers to a thousand a kilometer is literally 1,000 meters hecto refers to a hundred a hectare meter hundred meters deca refers to ten deci refers to 1/10 so decimeter literally 1/10 of a meter centimeter 100th one hundredth of a meter milli refers to one thousandth