While critical thinking is a foundation rather than a brick, how you build that foundation depends on the learning process itself: exposing students to new thinking and promoting interaction with that thinking in a gradual release of responsibility approach.
Question stems can be a powerful part of that process no matter where the learner is. They can be used as metacognitive and higher-order thinking prompts for class discussions, prompting, cueing, pre-assessment, self-assessment, formative and summative assessment, etc.