1
Extracurricular is one word.
The word extracurricular comes from the two words " extra & credit ". So since there is only one ful word that is in the word " extracurricular " extra is the root word.
* extraordinary * extraterrestrial * extracellular * extrasensory * extravaganza * extravagant * extracurricular * extradite
In (proper!) UK English, it's written with a hyphen. I don't know about US English or other variations of English. If you Google it, you'll find all three forms widely used!
Two words - "one day".
They are two words conjoined to be one.
It is two words. Writing it as one is acceptable in the UK and is referred to as a "Britishism." But in American grammar, it is always two separate words.
Extracurricular
ExtraOrdinary ExtraTerrestrial ExtraCurricular
"After school" is typically written as two words.
It is two words take it from a 7th grader
I recommend class work, as two words.