Ten favorite unit studies from the archives: 1. The Transcontinental Railroad 2. The Horse 3. The Eiffel Tower 4. The Oregon Trail 5. Maine 6. Laura Ingalls Wilder 7. The First Moon Landing 8. Winnie-the-Pooh 9. Leeuwenhoek’s Microscope: A Unit Study 10. E.B. White: A Unit Study Ready for More? View all of our unit studies! You can also browse our units by date.