Hi, a
mantra can be a resource that contains short, memorable information that's easily assimilated, it's one way to support children in remember their right to be safe from harm, saying no/stop that helps others moderate their behaviour and also to understand the expectations for own behaviour in the setting and how personal actions impact on friends.
You could use or adapt the suggestions you've been given and make a poster - as complex or involved as you want
Google image search for
classroom mantra
Best wishes