EC complete sentences????

I’m not sure how I should approach the EC section of the UC app.
DO I WRITE IT LIKE THIS:
Activity: Model UN
Description: Member 9-12th, Co-pres 12th, head delegate 12th

OR THIS:
Activity: Moadel UN
Description: I was a member for 9th-12th grade. As Co-president, I reminded members of important dates and info…

If I recall correctly, there wasn’t enough space to write out full sentences.

Use the first method. If you have space, do the description with as much info as possible.
ALso, I would say:

Description: Head Delegate 12th, Co-President 12th, Member 9th-12th

You want them to see the “best” part first.