Klassenfahrt mit Opa is the third book in Sarah Welk’s Spaß mit Opa series, aimed at children aged 9 and up. The story follows Jonas, whose school trip is at risk when one of the accompanying teachers injures themselves just before departure. Fortunately, Jonas’s grandfather, Opa Franz, steps in as a chaperone. With his cheerful demeanor and inventive ideas, Opa Franz ensures the trip is memorable. He transforms a planned hike into a beach party, organizes a guitar concert for homesick children, and arranges a spectacular farewell celebration. The book is filled with humor and heart, celebrating friendship, school life, and the joy of embracing life’s surprises