Children love looking at books with others. Here are a couple of books that children might sit down and want to look at with a grandparent.
Time for Kids Big Book of Why, 1001 Facts Kids Want to Know from (Time for Kids Magazine) by Editors of Time for Kids Magazine
National Geographic Kids 125 True Stories of Amazing Animals: Inspiring Tales of Animal Friendship and Four-Legged Heroes, Plus Crazy Animal Antics by National Geographic Kids
Guinness World Records books by Guinness World Records. These books are filled with pictures and facts that kids find fascinating.
Of course, any book a child would like to share or read with an older person would probably be welcomed.