Note: in BRIT, also use 'extra-curricular'
1.
Extracurricular activities are activities for students that are not part of their course. (FORMAL)
Each child had participated in ~ activities at school.
...extra-curricular sport.
ADJ: ADJ n
2.
Extracurricular activities are activities that someone does that are not part of their normal work. (INFORMAL)
The money he made from these extra-curricular activities enabled him to pursue other ventures.
ADJ: ADJ n