Police are investigating the fire at Impington Village College.
Emergency services were called to the college site in New Road at about 10.30pm on Sunday (3rd May) and found a large skip on fire.
Sergeant Emma Hilson from the South Cambs neighbourhood team said: “It is believed this was a deliberate act and we’re keen to hear from anyone who may have witnessed any suspicious activity or unfamiliar people in the area around the time of the incident.
“Thankfully the damage to the school was fairly minimal and staff and teachers caring for key workers children have been able to resume as normal this morning.”
Anyone with information is asked to call police on 101 quoting reference 35/29200/20 or report online.