Alice keeps a perfectly round skipping stone in her pocket to remember her grandfather by — but the stone goes missing.  It looked just like a regular stone, but Alice knew it was different: It was perfectly round so you could use it to trace circles, and sometimes she could trick her dad into thinking it was a quarter. It was also how Alice remembered her grandpa, who taught her how to skip stones, and who passed away last winter.  Alice brings the stone to school for Show and Share, but when her classmate asks to see it again at recess, Alice discovers that the stone is gone! Her...