Rather than saying the electrons transition between energy levels to produce the colors in fireworks, how might you refine this description using your new knowledge of the quantum mechanical model? What does this tell you about the energies of the orbitals?

Technically, "quantum theory" is actually just the theory associated with quantum mechanics, ie; the theory of any objects isolated from their surroundings but, because it is very difficult to isolate large objects from their environments, it essentially becomes a theory of the microscopic world of atoms and sub-atomic particles.