Center of Gravity
In Shaunta Grimes' middle-grade novel Center of Gravity, a girl loses her mom, and her dad remarries quickly, so she must rebuild her life and friendships.
Tessa is an anxious person, but it's become worse since her mother died a few months ago. To calm herself down she cuts out photos of missing kids—from milk cartons—and keeps them in a file. It helps her feel like she's not alone.
When her dad announces suddenly that he's getting married—and that they're moving, Tessa must navigate new friendships and a new stepmother. She knows she should let go of old habits, but that's easier said than done. Her struggle is one that many readers will understand.