Der Vierzehnte Goldfisch by Jennifer Holm

In this whimsical and heartwarming tale, a young girl named Ellie embarks on an unexpected journey of discovery when her grandfather, a scientist with a penchant for the extraordinary, finds a way to reverse aging and transforms into a teenager. As Ellie navigates the challenges of middle school, she learns valuable lessons about family, friendship, and the wonders of science. Together, they explore the complexities of growing up and the importance of embracing change, all while unraveling the mysteries of life and the pursuit of dreams.