Blow your students' minds with this fascinating lesson that walks them through the facts of psychology to arrive at the astonishing answer to the ancient riddle-question: If a tree falls in the forest and there is no one there to hear it, does it make a sound? This one-period activity is great for kick-starting an energetic discussion about the nature of reality and our perceptions of it. Students are fascinated to learn that the world outside of our senses is not quite the same as the world that our brains present to us. The two-page interactive handout guides the students through the learning process about sensation and perception until they are ready to apply their new concepts to the famous question, which can now be answered in the negative. The teacher’s key allows you to lead them confidently through a review of the lesson and/or a discussion of its implications, and the teacher's guide gives valuable tips about how to maximize your students' experience with the activity.