SOLVED. YA fiction To guard against boredom she invents a game for herself in which she is the subject of an experiment and the rest of the world is there just so that some scientists can see how she reacts to things [s]

[Rosa]

A couple of years ago I read a short novel with solipsist themes I can't remember the name of. It was about a girl whose artist parents move every few weeks or so. She likes her nomadic lifestyle and is horrified to learn that she is going to stay in one California town for a full six months. To guard against boredom she invents a game for herself in which she is the subject of an experiment and the rest of the world is there just so that some scientists can see how she reacts to things. She writes letters to the scientists in her notebook.

At her new school she befriends two people: a popular girl and a not-so popular girl. The rest of the novel is about her friendships with them deepening to the point that she doesn't want to move when the six months are over and no longer needs to play her game.

[Rosa]

I finally found this book! It's The Ashwater Experiment by Amy Koss.

[Rainbowheart]

The Ashwater Experiment for the link.