“We read this YA novel as a class assignment in 8th grade (1975) so it was probably a Scholastic publication. Girl has a hobby of raising pet birds (canaries?) and cares for sick birds. She has a glass-enclosed birdcage for this purpose, which is the only detail I really remember. She befriends/dates a “bad boy”. I’m very vague on the plot, but I think he is accused of doing something bad, but is innocent, and she stands by him. In the last scene, at her house, they kiss and she hears a bird singing “or maybe it was my heart”. The Troublemaker By Robert McKay thanks to reader Sylvia!