Each learning path is one chapter: a guided route through a topic, one small course at a time. Pick a class to see its chapters in order.
You pull your hand away from a hot pan before you even think about it. A plant on a windowsill bends towards the light. Both are living things responding to a change around them. In this chapter you see how nerves carry messages in animals, how a reflex works, what the parts of the brain do, how plants respond without nerves, and how hormones control growth in plants and animals. Python helps you time reflexes and model hormone levels.