Jack and Annie are taken back to the prairie in 1870's by their magic treehouse. During the trip they meet children and a teacher who show them how different and good they have it in the modern world.
Upon arrival Jack and Annie realize how life was very different in the 1800's. They see wagons and people travelling the prairie. After exploring they find a nearby school and decide to join the class for the day.
At a one room school house, Jack and Annie meet and spend the day with several children of different ages. They are surprised to find such a wide range of ages in one classroom and a teenager, Ms. Neely, as the teacher. After learning about grasshopper attacks and receiving a slate to write a message on, they decide it is time to return home.
While walking back to the magic tree house, Jack and Annie spot a twister in the distance. They debate whether to leave but decide they must warn the teacher and students and tell them about the cellar hidden below the schoolroom.
When they get back to the school, they find the children huddled together and the room being torn apart by the twister. They all safely make it in the cellar and wait out the storm.
As Jack and Annie are leaving, Jeb, the school "bully" catches up to them to tell them thank you. Jack and Annie realize that Jeb has had a hard life and isn't the bully they first believed him to be. With their special message in hand they return home to discover what adventure awaits them next.