Sensory Clues:
* A sudden, cold breeze: Even on a warm day, a chilling gust of wind could make the children feel uneasy.
* A whisper in the wind: They hear their names called softly, even though there's no one around.
* A strange scent: A faint, unsettling smell like damp earth or decaying leaves that lingers in the air.
* Footsteps behind them: They hear the sound of someone walking behind them, even though they haven't heard anyone approaching.
* A flickering shadow: They catch a glimpse of a dark figure darting behind a tree or a building as they pass.
Visual Clues:
* A figure in the distance: They spot someone standing at the edge of the woods, watching them as they walk.
* A broken branch: They notice a branch that wasn't there before, seemingly broken with no reason.
* A strange object: They find something unusual lying on the path, like a doll or a piece of broken glass, out of place and unexplained.
Let me know if you'd like me to elaborate on any of these or if you want some more ideas. I'm here to help you create a creepy and suspenseful story!