Define homeostasis and use a real pulse-recovery investigation as evidence that the body actively works to keep internal conditions stable.
Homeostasis is the body's constant work to keep internal conditions -- temperature, water level, blood sugar, heart rate -- steady, even while the outside world keeps changing. It is not that these things never move; it is that the body actively pushes them back toward a stable target range whenever they drift. Sweat cools you down when you are hot; shivering, which is rapid muscle contraction, generates heat when you are cold. Both are homeostasis in action: different actions, same goal, stay stable.
You can watch homeostasis happen with nothing but a clock and your own pulse. Exercise raises heart rate because muscles suddenly need more oxygen and fuel delivered faster. Once you stop, the body does not leave heart rate high -- it works to bring it back down toward its resting range as quickly as it reasonably can. How fast that recovery happens is actually a real measure of fitness.
Mastery looks like: They can define homeostasis, describe at least two real body examples, and read a set of pulse data to identify the recovery trend.
Common stumbles: Thinking homeostasis means a value never changes at all, rather than that it is actively corrected back toward a stable range after it changes.