When we speak about time, we often say like one-twenty one. Is it common to write time like this, especially to teach primary students to write time like this ?
It is very rare to write
one twenty-one to refer to time, and if I saw it written this way I might not even realise the speaker was talking about time. For this reason students would not be taught to write time like this. The only case for writing the time out in words is if you are writing speech, and even then this would be rare.
It is usual to use numbers in this way though. You can write
1:21 as a short way of noting down the time. This is easily recognisable as time.
Note: It is important to include
pm when writing the time. In most English-speaking countries it is becoming common to use 24-hour time, for example:
01:21 instead of
13:21 instead of
However it is a good idea to include "am" in all cases where it might be ambiguous, so