The first is a Cows Moo Softly poster which I use as a reminder for variables which change, stay the same and are measured/observed when we are conducting fair tests.
Next I have 3 job role posters. These roles are used is some Australian schools, particularly those using Primary Connections science units.
In the lower school, they recommend that teachers limit the roles to 2 - Manager and Speaker. Later, they introduce the Director role.
Download them for free from my TpT store.