Scales are small plates that grow out of the skin of fish and reptiles. They overlap, so if you run your hands down a fish or snake from its head to its tail it will feel smooth, and if you run your hand the other way it will feel rough.
Your scalp is the skin on top of your head, where you normally grow hair. When men go bald you can easily see their scalp. The man in the photo has his scalp showing through a scar.
A scar is a mark on your skin that shows where it has healed after it was damaged. Scar tissue can also form inside you if you have an internal injury. The man in the picture has a scar from donating a kidney.
A shell is the hard outside coating found on many animals. Snails have shells that form a spiral that was built up as the snail grew bigger. crabs and turtles have a hard shell that perfectly fits the animal inside. Most animals that have shells can hide inside them if they are scared.
Your shins are at the front, bottom part of your leg between your knee and your foot. There is not much fat or muscle on your shins, so it hurts to get hit there and shins are usually very easy to bruise.
Your shoulder is the joint between your arm and your body. People sometimes tap you on the shoulder to get your attention. The woman in the picture has a rat on her shoulder.
Your skeleton is made up of a number of bones, which hold you up. Your bones are connected to each other by joints, such as your knee and elbow, which let you move around. The skeleton in the picture is a cat skeleton.
Your skin is the largest organ on your body. It covers you completely and protects your muscles and other organs. Your skin has glands on it that produce oil and sweat, and your skin has follicles in it that grow hairs.
Skulls are a bony structure that is found inside your head, and in the head of almost all animals. The top part of the skull is called the cranium and the bottom part is called the mandible. Your mandible is more commonly called your jaw, and is the part that moves up and down as you chew or open and close your mouth. The picture is of a fox's cranium.