Schools are warning parents that a new location-sharing feature in Snapchat could put children at risk.
Snap Map lets users share their exact location with people on their "friends" list in real time.
In a letter seen by the BBC, one school said the map raised "serious safeguarding concerns" because children could be tracked on the map.
But Snap, the company behind Snapchat, says the feature is opt-in and can be switched off at any time.
Snap Map was launched on 21 June and lets people browse a map of photos and videos that have been shared publicly.