Why are the teenager students and older required to use ball pen rather than pencil ?

Part of it is to avoid cheating. Some students change their wrong answers upon receiving their marked tests and then tell the teacher that he/she made a mistake in grading the paper. Using pen makes that more difficult. Also, pencil lead sometimes smears and fades on paper. Have you ever written a whole essay in pencil and found that the side of your hand was completely smeared with lead? Pen is often much cleaner and lasts longer, provided the student doesn't make a lot of messy errors.

I think the purpose is for us to write one's answers with as little erasures as possible. In one of our high school projects in the past, we had to write 10 pages of biographies of several saints using a ballpen, with no erasures. This purpose is more emphasized in college, I believe. By that time, they're training you to be sure of your answers and to avoid any erasures in preparation for the licensure examinations.

Older student should have the capability to write something without erasures, it also a required writing medium in some professions

teenagers are prone to cheating ergo, the use of ballpens during tests would lessen their chances because they cannot erase their wrong answers and replace them with the correct ones upon checking their test papers

They should be able to write better now and no need of frequent erasures!

Another useless skill Filipinos seem to excel at...writing with a bolpen. Lulz

to make them practice writing without alot of erasures..

There are many different instruments to write with. Each has a specific use. Students should be able to make finished work with a ball point pen. Do the draft, or rough copy with a pencil and the finished work with a ball point pen.

I agree with PurpleRose328. It is to avoid too many erasures.