The policing neighbourhood team work with schools in our area.  They often speaks to pupils in assembly, in class, 1 to 1 if requested.  They are always very positive but let the children know how to stay safe locally, what to do in an emergency and who to call, dangers to be aware of and consequences of actions.  They are always aware to be age appropriate.

https://nelwatch.org.uk/neighbourhood-watch/support-for-groups/meet-your-local-policing-team/