No rules for critical thinking will work for everyone. There is no single answer. Be aware of the students' frame of reference.
Incongruity challenges students.
Give examples that have more than one correct answer. Ask the students to generate examples of their own . Tell the students that it is okay to be wrong as a stage in their learning. Ask students for specific examples and details that support their ideas, assumptions, and preconceptions. Perhaps critical thinking is knowing what questions to ask.