This is a Canadian postage stamp showing Queen Elizabeth II. We can tell it might be quite old because...

As elementary school children learn about what history is and what it means, they will also begin to understand the various sources from which historical information can be gleaned. This may include looking at photographs, reports, artifacts and other evidence. They are also encouraged to observe the environment around them for possible sources of evidence. Asking sensible questions about what this evidence represents is an important skill which young children sometimes find tricky to develop.