A map is much smaller than the real place. So how can a map tell you how far something is? It uses a scale bar.
Key idea
A scale bar shows how far a length on the map is in real life. Count the lengths, then use the scale to find the real distance.
Worked example: From the farm to the school
The farm and the school are 4 squares apart. One square is 10 miles. How far is it?
- Count the squares: 4.
- Skip-count by 10 for each square: 10, 20, 30, 40.
Answer: 40 miles.
Why it works
The mapmaker shrinks everything by the same amount. If one square stands for 10 miles everywhere on the map, then 4 squares must stand for 4 tens: 40 miles. That is why the same skip-counting from counting by 5s, 10s and 100s works.
Common mistake
Places that look close are not always close. On a map of your town, one finger-width might be a few blocks. On a map of the whole country, the same finger-width might be hundreds of miles. Always check the scale bar.
For the grown-up. Compare a map of your town with a map of your state. Put a finger on each. Ask, "Is my finger the same distance on both maps?"