Rocks have been used to smash windows at a school in Altwood Road in Maidenhead.
Three windows in the gym were broken sometime between Saturday and yesterday, a police community messaging alert said.
It did not say which school was targeted.
The alarm code entry system to the building was also smashed, but no-one went inside.Contact 101 or Crimestoppers on 0800 555111 with information.
Top Ten Articles
The Met Office has issued a yellow alert for Windsor and Maidenhead, Slough and Wokingham, warning that rain moving eastwards across the south of the country may turn to snow in some places.