By Jennifer L. Holm
Ellie's scientist grandfather figures out how to reverse aging, and turns up on the doorstep as a grumpy thirteen-year-old.
Ellie is just starting middle school when a rude teenage boy shows up at the door wearing her grandfather's clothes and complaining like an old man, because he is her old man. Grandpa Melvin, a lifelong scientist, has cracked the secret to reversing aging and tried it on himself, and now he is stuck looking thirteen. He needs Ellie's help to sneak back into his old lab and rescue his research before anyone finds out, and somewhere along the way she catches the same bug he has: the itch to know how things actually work.
This is the friendliest possible on-ramp to science fiction, because the science is real and the setting is your own kitchen. There are no aliens or spaceships here, just one big what-if (what if you could stop getting older?) dropped into an ordinary family, and a girl discovering that scientists are simply people who refuse to accept that something is impossible. It is short, it is funny, and the chapters fly by. Underneath the comedy it is asking whether living forever is really such a good idea, which is a big thought handed over with a very light touch.