The One in the Middle is the Green Kangaroo by Judy Blume, 1981.

Freddy Dissel hates being the middle child in his family. Before his younger sister, Ellen, was born, he had his own room. Now, he has to share with his older brother, Mike. Mike gets new clothes, while Freddy has to wear Mike’s hand-me-downs. Mike and his friends won’t play with Freddy because he’s too little to play their games, and Freddy can’t play with Ellen because she’s too little for him. Freddy hates always being caught in the middle with nothing special to distinguish him from his siblings.

Then, Freddy finds out that there’s going to be a play at his school. Seeing it as his chance to do something special that his siblings haven’t done, he asks his teacher if he can be in it. At first, she tells him that the only kids in the play are older kids, around his brother’s age, but seeing his disappointment, she says that she’ll talk to the teacher in charge of the play, Ms. Matson, and see if there’s a part for him.

When Freddy gets his chance to try out for a part, he demonstrates to Ms. Matson that he can speak up loud and isn’t afraid to hop around on stage in front of everyone. He’s thrilled when she gives him the part of the green kangaroo. Now, his family and everyone else can see him do something that his brother and sister don’t get to do!

Even though he does get a little stage fright right before the performance, working through it and playing his role as the green kangaroo gives Freddy new confidence. From then on, he’s not just Freddy the middle child but Freddy, the one and only green kangaroo!