Here's a procedure that works for any decimal:
Step #1). Read the decimal out loud.
Listen to yourself as you read it.
Step #2). Quickly, before you forget it, write down
what you heard yourself say.
When the decimal is 0.5 . . .
Step #1). Read the decimal out loud. Say "five tenths".
Step #2). Write that down. " 5/10 " .
You may simplify the fraction if you can and if you feel like it.
To simplify a fraction, divide the top and bottom numbers by
their greatest common factor.
5/10 simplified becomes 1/2 .