What is rain, and why is it good? Find out in Rain! . The fiction book that accompanies this title is Is That Rain? . Oxford Reading Tree Explore with Biff, Chip and Kipper is a series of paired fiction and non-fiction books linked by curriculum-related topics. Each pair consists of an engaging story featuring well-loved characters and a compelling non-fiction book. These topic-linked pairings will develop and deepen their reading comprehension and foster a love of reading across both text types.