Are the tenses in this sentence acceptable?or should past simple be used (I was a good student)?
***** NOT A TEACHER *****
(1) May I add a note to the moderator's excellent answer?
(2) I am a learner. I like clear rules. Your students also probably feel the same.
So
maybe it would give your students peace of mind to follow the "rule":
Since "told" is in the past, make it "was."
(3) When your students learn more English, then they will be able to understand
that many native speakers feel more comfortable using "am" if the situation -- as
the moderator told us -- "is still true."
P.S. Of course, there are exceptions. You have to say:
My teacher
told me that the moon
is X miles from the earth. (That situation will be true
forever -- presumably.)