Mckenna (american girl: girl of the year 2012, book 1)

Ten-year-old McKenna has always been a good student-and great at gymnastics. So when her grades suddenly begin to fall, her teacher suggests a little extra help from a tutor. McKenna is horrified until she meets her tutor, Josie, a super-confident girl who also happens to be in a wheelchair. Josie encourages McKenna to focus on her strengths and work toward her goals one day at a time. But just as McKenna begins to shine in school, she's sidelined with a gymnastics injury--and her confidence unravels. Now she's worried about her grades and earning a spot on the competitive gymnastics team. Can she find a way to believe in herself again?