'Practice' is a noun (a thing).
'Practise' is a verb (an action).
And no – there is no logic to the way the English language works!
Handy hint – To help you remember, compare the spelling of 'advice' and 'advise'.
An easy way to remember how to use practice/practise is to think of the words 'advice' and 'advise'. They have the advantage that you pronounce them differently and so they are easier to remember.
I may give advice to someone. Because I am giving them a 'thing' the word 'advice' is a noun and has a 'c'.
I would advise someone to read these notes carefully. In this case I am doing something so 'advise' is a verb.
It is the same with practice (noun) and practise (verb).
Working the other way around - words ending in ICE usually means the word is a noun, like ICE; and words ending in ISE usually means the word is a verb.
The word 'practising' always has an 's' because it is always a verb.
We often get caught out when writing reports for parents. These examples may help you to avoid the pitfalls.
With practice, he will improve his ball control.
If he practises with ball control, his skills will increase.
Harry should prepare for his exam by using his book of past papers as practice. (Here practice is being used as a noun – a thing.)
Harry should prepare for his exam by using his book of past papers to practise. (Here Harry is being told to do something – a verb.)
Jane should practise sketching at home, using the pad she has been given.
We have been practising for our dance show in every spare moment.