I am the owner of a pet store. If I put in one canary per cage, I have one bird too many. If I put in two canaries per cage, I have one cage too many. How many cages and canaries do I have?
If you put one canary in each cage, you have an extra bird without a cage. However, if you put two canaries in each cage then you have two canaries in the first cage, two canaries in the second cage and an extra cage.
A clock. It runs all the time, it “sings” for hourly chimes, cuckoos or alarms, it doesn’t have a head (but does have hands) and you look a clock in the face to tell the time.
I saw a strange creature,
Long, hard, and straight,
Thrusting in a round, dark, opening,
Preparing to discharge its load of lives,
Puffing and squealing noises accompanied it,
Then a final screech as it slowed and stopped.
Note: This may not be appropriate for younger ages.