The Hidden Threshold: Classroom 13 1/2 series

Something strange is happening in Classroom 13½. When Theo and his friends discover an unusual mathematical pattern hidden inside their classroom, they realise it is more than just a puzzle. The mysterious spiral that appeared before has begun to reveal new secrets — secrets that connect numbers, patterns, and the past in ways none of them expected. As the group investigates deeper, they uncover clues hidden in diagrams, symbols, and unexpected places around the school. But every answer leads to another question. What does the spiral mean? Why does it seem to react to Theo? And what happens if they follow the pattern too far? Blending mystery, mathematics, and adventure, The Hidden Threshold invites readers to explore the excitement of discovery. Along the way, students encounter puzzles, logical challenges, and ideas that show how mathematics can reveal hidden patterns in the world around us. Perfect for readers who enjoy mystery stories, classroom adventures, and the thrill of solving problems together.