Now consider a polar bear on the ice.

A polar bear on the ice. Its fur is very thick.

Its fur is very thick, so it keeps the warmth in.

So the polar bear stays warm on the ice: keeping warm or cool.

Now consider a woodpecker on a tree.

A woodpecker, its sharp beak driven into the bark.

Its beak is hard and sharp. The beak chips into the wood, where insects live.

So the woodpecker reaches its food.

Now consider a porcupine.

A porcupine. Its back is covered in long, sharp quills.

Its back is covered in long, sharp quills. A fox cannot bite it.

So the porcupine stays safe.

Now consider a camel in the desert.

A camel on the sand. Its feet are wide and flat.

Its feet are wide, so they do not sink into the soft sand.

So the camel walks about where it lives.

Six body parts, six jobs: moving about, getting food, keeping warm or cool, staying safe.

Every one of these parts does a job. Every job helps the animal survive.