Lengths
Measuring Lengths
Method Measure Length with Objects
To measure the length of an object, use small things like blocks or erasers. Line them up next to the object and count how many fit along its length.
Example
The cucumber measures 4 erasers long.
Length Units
We can measure length using different units like blocks or erasers. But these units are not the same for everyone. Your friend might have a longer eraser than yours, making it hard to compare. To solve this, mathematicians created a universal unit called the meter, so everyone can measure and compare lengths the same way.
Definition Units of Length
- Centimeter \(\left(\mathrm{cm}\right)\): A small unit of length, about the width of your finger.
- Meter \(\left(\mathrm{m}\right)\): A longer unit of length, about the height of a girl.
Perimeter
Definition Perimeter
The perimeter of a shape is the total length around its outside edge.
To find the perimeter, imagine walking around the shape like it’s a park. Count the number of unit lengths along each side as you go.
Example
Find the perimeter of the red shape:
The perimeter is 8 units.