I am a student trumpet player in 8th grade, and for our concert we are playing centuries which is cool and all, but in the solo I have at the beginning which is quite simple. I transition from A to high E, and it just sounds awful. I can play both the A and the E separately very well and in tune, but when I go from A to high E quickly, I just don't understand what happens. Any help is greatly appreciated. (PS: I am playing a Bb trumpet)
To go from second-space A to top-space E you go from valves 1+2 to open. On trumpet, transitions between different pitches will be hampered by poor synchronization between valves, tongue and embouchure.
See if you can play the line cleanly by keeping 1+2 pressed (E in the top space can be played on open or 1+2). If you can then it's probably a valve speed issue, and it's something you can work on separately. The fact that the notes work when you play them individually also suggests that it's a fingering issue.