Pupils are expected to understand ratio and proportion, including map skills by year 7. As they get older they are also expected to understand how to use ratio and proportion to calculate quantities.
The Ordnance Survey’s Mapzone site has some excellent resources and videos for learning about ratio and map skills.
Another key use of ratio in the real world is scale drawings. Pupils create these in their Art and DT lessons. An excellent resource for trying at home is the Khan Academy (well worth a look for lots of other subjects too).