The C vs. S Dilemma

Defense or defence?
Offense or offence?
Practise or practice?

This distinction may be fast becoming an extinction, but it appeals to the English scholar in me. Most people either use one or the other regardless of the situation; others make the distinction as a result of a lesson crammed long ago, however, the rationale behind that distinction has been forgotten.

The suffix –se applies when the word is being used as a verb.
Example: I will practise the piano today.

The suffix –ce applies when the word is being used as a noun.
Example: Will you attend piano practice today?