By Tom Percival
A cheerful girl picks up a Worry that only gets bigger the more she keeps it to herself, until she learns the one thing that makes it shrink.
Ruby is a happy, adventurous girl until the day she notices a Worry. It's a small yellow blob at first, easy to ignore, but the more she tries not to think about it, the bigger it gets. It follows her to school, onto the bus, into the movies, everywhere, until it's an enormous yellow cloud blocking out everything else and she can't enjoy anything. As the Worry grows, the color drains out of the whole book and the pages go gray. Then Ruby meets a boy with a Worry of his own, and when they finally start talking about them, both Worries begin to shrink, and the color comes flooding back.
For a child who lies awake with a knot they can't name, or who's gone quiet and clingy lately for reasons you can't pin down, this is the one I'd reach for. The Worry grows on the page precisely because Ruby is trying not to look at it, and that gives a young child a way to see what happens inside them when a worry gets stuck. Better still, the thing that shrinks it is something they can actually do: tell someone. Not 'don't worry,' which no child has ever pulled off on command, but say it out loud to a person who listens. Your child feels understood here, and comes away with a real move to try rather than a pat on the head.