A lot of the time, it's not really the best idea to have things full size. A map would be useless if it was full size, a toy car doesn't really want to be the same size as a normal car.
When we have this issue, we use a scale diagram or a scale model.
What is a scale diagram?
A scale diagram is just a diagram where everything has been reduced by the same factor, it could be half the size, a tenth of the size or anything else.
How are scales written?
Scales are written as a ratio such as 1: 100 or 1:50 000
What does this mean:?
Scales are read left to right. The scale 1:100, for example, would mean that every 1 unit of length on the scale is the same as 100 units in real life.
So something that was 2 cm long in real life would be 200 cm long in real life.
Example 1: A model car is 3m tall. If the scale is 1:100, how tall would the model car be?
We know that there is a factor of 100 and that the model is smaller
All we need to do here is change the units into cm and divide by the scale factor.
300 ÷ 100 = 3 cm
Example 2: A model is made of a 2 m tall man. If the model is 4 cm tall, what is the scale?
The first thing we should notice here is that the units are different, so we need to make them the same.
2m = 200 cm
Step 2 is to write these numbers as a ratio (remember the model comes first))
Out third and final step is to simplify this ratio.