In the third book of the American history cluster, Jack andAnnie are whisked to a midwestern prairie in the 1870s. They visita one-room schoolhouse and learn about the hard life of thepioneers. When they return to the magic tree house, Jack and Anniespot a twister on the horizon. Is there time to warn the teacherand the children back at the schoolhouse? Or should Jack and Anniejust save themselves?