Nice first android app.
To make this concept powerful you need to add a persistence layer (database interactions). That way people can track their progress over a period of time. Also a touchscreen on a phone is a very awkward interface for inputting 6 courses over and over again to calculate an average. You would be much better off having the persistence layer and adding delta updates .. that is the ability for the user to make incremental changes to courses, semesters and assessments over a long period of time.
You will want to use an SQL database. Android doesnt make this particularly easy so I would follow some very good tutorials out there. You will want to brush up on SQL. Id recommend tables for
1) SEMESTER (id, start_date, term{1,2,3})
2) COURSE (id, semester_id, course_code, units, completion_date, mark)
3) ASSESSMENT (id, course_id, weight, mark, completion_date)
This gets object mapped to:
class semester has List<Course>
class course has List<Assessment>
~Thats just from the top of my head. Obviously look at your skills and any requirements you think you want to add. For example you could have both mark and desired_mark or something to help calculate marks needed on exams or whatever.
