Twelve books in the popular children's series. Dinosaurs Before Dark/The Knight at Dawn/Mummies in the Morning/Afternoon on the Amazon/Midnight on the Moon/Ghost Town at Sundown/Tonight on the Titanic/Tigers at Twilight/Dingoes at Dinnertime/Civil War Sunday/Twister on Tuesday/Earthquake in the Early Morning)
Books #1-4 of the Magic Tree House series by Mary Pope Osborn. Titles include #1 Dinosaurs Before Dark ~ #2 The Knight at Dawn ~ #3 Mummies in the Morning ~ #4 Pirates Past Noon.