In the little fairytale town of Lumina, there lived a bright, curious boy named Daniel. A place of ethereal beauty, Lumina was blessed with a splendid meadow, a sparkling stream, and an ancient apple tree under which children would gather to listen to tales from their favorite storyteller.

One sunny afternoon, as Daniel was playing with his marbles, an elderly man with a shock of white hair, bushy mustache, and kind, twinkling eyes walked into the meadow. He introduced himself as Albert Einstein, a physicist from a faraway land. The children gasped in awe. Einstein was not just a physicist; he was the creator of the mystical 'theory of relativity'!

Einstein decided to hold a physics class under the apple tree and chose Daniel as his eager assistant. The central mystery that Einstein presented was the baffling disappearance of a grand school in space. The news had traveled across galaxies, making it a universal conundrum.

Einstein, with Daniel by his side, explained how his theory of relativity worked in the simplest ways, using apples from the tree and Daniel's marbles. However, as the class proceeded, a daunting challenge presented itself. Neither Einstein nor the children could initially figure out why a whole school could disappear in space.

Suddenly, Daniel's marble rolled off his palm, inspiring a twist in the tale. Einstein used this event as an analogy to propose that maybe the school hadn't disappeared, but merely moved due to a warp in space-time - just like Daniel's marble!

"Remember, space and time are woven together in a fabric. A heavy object can cause a warp or dip in this fabric," he explained. The children gasped, their eyes wide with wonder, as they began to comprehend the complex mystery.

Using imaginary lines, Einstein, with Daniel’s help, demonstrated how the warped space-time fabric could cause the school's perceived disappearance. After much deliberation and a challenging Q&A round, the children finally understood the mystery. It wasn't a vanishing act, but a matter of perspective and relativity!

Einstein smiled at their acute understanding. The children, led by Daniel, had triumphed over the challenge, solving the enigma of the missing school. They had taken their first successful steps into the magical world of physics. Their enthusiasm and Einstein's teaching breathed life back into the fairytale town of Lumina.

The happy ending wasn't just about solving the riddle. It was about the birth of new curiosity among the children of Lumina and their newfound appreciation for the mysteries of the universe. Daniel, once a child curious about simple marbles, was now intrigued by the marvels of space-time!

That night, Daniel dreamt of floating schools, warping space, and twinkling stars. He woke up smiling, his heart filled with joy and his mind brimming with questions about the universe. And under the apple tree, waited Einstein, ready with another captivating tale, another riddle, another day of dreaming and learning.