THE BEST SICK DAY EVER and the animals in the zoo feature in this striking  picture book debut.     Friends come in all sorts of shapes and sizes. In Amos McGee's case, all  sorts of species, too! Every day he spends a little bit of time with each of  his friends at the zoo, running races with the tortoise, keeping the shy  penguin company, and even reading bedtime stories to the owl. But when Amos  is too sick to make it to the zoo, his animal friends decide it's time they  returned the favor.     A Sick Day for Amos McGee is a 2011 Bank Street - Best Children's Book of  the Year and the winner of the 2011 Caldecott Medal.