Creativity, or creative thinking is often juxtaposed with critical thinking, so for starters, I want to briefly differentiate these two modes of thought. Critical thinking is convergent, selective, sequential/linear, purposeful, and logical. Creative thinking is divergent, generative, random, playful, and innovative. When we make new connections between things, we are being creative. When we analyze those connections, we are being critical.
Many questions in school are critical in nature, meaning that they typically ask students to recall, analyze, or synthesize answers. So in order to teach students how to think creatively, teachers must add creative thinking questions to their repertoires. Here are some examples from Tom Wujec's book Five Star Mind: Games & Puzzles to Stimulate Your Creativity & Imagination.
Which is bigger red or brown?
Which is more massive, stretch or yawn?
Which is funnier, Q or Z?
Which is slower, might or courage?
Which is more accommodating, the sky or a century?
Questions like these prompt or encourage students to make connections between things they wouldn't normally connect. This is the very nature of creativity. With practice, students will be able to connect just about anything to anything else. In other words, they will become more creative. Here are more of my own examples:
What color is honor?
What shape is sour?
What personality does the number eight have?
What does the letter 'A' smell like?
What texture goes with Haiku?