Primarily US focussed but a really useful site for schools to refer to and it also includes a cyber security self-assessment:
https://k12cybersecure.com/
NCSC alert UK focussed but good guidance for all educational establishments:
https://www.ncsc.gov.uk/news/alert-targeted-ransomware-attacks-on-uk-education-sector
And cybersecurity resources for schools (in English and Welsh): Resources for schools
Guidance from CERT New Zealand:
Downloadable copies of cybersecurity information cards for schools from NCSC:
https://www.ncsc.gov.uk/information/resources-for-schools