Rebel girls (Chapter books) volume 3
"Junko is bad at athletics. Really bad. Other students laugh because they think she is small and weak. Then her teacher takes the class on a trip to a mountain. It's bigger than any Junko's ever seen, but she is determined to make it to the top. Ganbatte, her teacher tells her. Do your best. After that first trip, Junko becomes a mountaineer in body and spirit. She climbs snowy mountains, rocky mountains, and even faraway mountains outside of her...