You have just buckled in for an airplane trip but as the plane begins to ascend, your ears begin to hurt. The pressure that is building as the plane rises presses against your ear drum and causes it to hurt. This happens to almost everyone who flies; once the airplane reaches its flying altitude the pain almost always goes away. Young children often suffer from this same type of ear pain after having a cold or the flu. This type of pain comes from an infection in the ear and must be treated by a doctor to get better. This series, titled "First Facts. Health Matters," presents simple, brief explanations about how things that affect the young reader happen. Each title contains a hands-on activity that illustrates the principles discussed in the book, or gives additional information. The glossary contains all the words that are in bold print throughout the text. An index and suggestions for further reading are included. This publisher maintains a web site, facthound.com, that directs children to resources chosen for age appropriateness. Each selection of resources is identified by typing in the book ID. Resources selected are then specific to age and the subject of the title. This management of resources is particularly helpful for this age group. All titles in this series have the same resource management page, and all titles are recommended for elementary classrooms and media collections.