Bear,
Think of it as having to make up for the difference.
What is the difference between:
1) what the page says the trumpet is in
and
2) what you have in your hand
That indicates
both the diff you need to read (up or down) and the key signature
Keep it simple:
page says trumpet in C
the key sig on the page is also C
you are holding a Bb trumpet
diff is??? Bb to C make up the diff... a whole step.
Help?
