A man reportedly exposed himself on the disused Wombourne Railway link and there have been reports of similar incidents in Baggeridge, Albrighton and Sedgley.
Wombourne High School warned parents and carers about the flasher who exposed himself on the Wombourne link.
Staffordshire Police is investigating the incident on the disused railway line which people use as a scenic short cut.
The Wombourne High School statement said: "Please be aware we have received notification a male individual exposed himself on the Wombourne Railway link. It is possible the same individual has been involved in similar event in Baggeridge.
"The police are involved in the investigations."
The school warned students to stay away from the railway link and under no circumstances to travel to school alone on the route.
The school statement added: "We recommend students avoid the railway link. Should students need to use this link we strongly recommend they are never alone."
There have also been reports of a man exposing himself in Albrighton and Sedgley.
Staffordshire Police has been contacted for comment.