Teachers often use analogies and are unaware of it—they are using them automatically. Whenever they begin an explanation with “It’s just like…,” “It’s similar to…,” or “Think of it this way…,” they are using an analogy to explain a concept to their students. An analogy is a similarity between concepts. Analogies can help students build conceptual bridges between what is familiar and what is new. Often, new concepts represent complex, hard-to-visualize systems with interacting parts (e.g., a cell, an ecosystem, photosynthesis).