Based on my personal experience about this "extracurricular activities" was:
❶ The student missed some of the lessons.
❷ Students can considered as excuse but not fully present.
❸ When there is a quiz ,assignment,test,etc. The particular student will missed this day because of his/him activities
❹ There are possible that the student will not be knew the lesson that teacher taught because he/she was not in there when this
❺ The possibility that the student academic performance was so high , but have the lowest result in exam.
A/N :My answer is only based on my own definition and there was no scientific basis on it. :D. Thank You.
--COLLINSDAX "at your service"