One sunny morning, Ben walked into his classroom and felt a chill. 'That's odd,' he thought.

As he settled at his desk, Ben saw a quick shadow dart across the room. He blinked.

He whispered to his friend Mia, 'Did you see that?' 'See what?' Mia asked, looking around.

The teacher, Mrs. Green, began the lesson, but Ben couldn't shake off the eerie feeling.

During break, Ben and Mia heard strange whispers coming from the book corner. No one was there.

The whispers stopped, and they bravely checked the corner. A book titled 'Ghosts' was on the floor.

Ben opened the book and found a bookmark. It had a message: 'Solve the riddle, find the truth.'

The friends decided to solve the riddle. 'What is always there but never seen at night?' it asked.

After thinking hard, Mia exclaimed, 'Shadows! Shadows disappear at night. It's so simple!'

As they spoke the answer, the mysterious shadow reappeared and turned into a smiling ghost!

The friendly ghost thanked them and explained he was a guardian of the classroom, keeping it safe.

Ben and Mia promised to keep his secret. The ghost vanished, and the classroom felt warmer again.