Arthropods are a group of animals that are invertebrates. There are more arthropods than any other kinds of animals on Earth. Arthropods have a type of skeleton outside their bodies called an exoskeleton. They also have segmented bodies and jointed attachments called appendages.
The exoskeleton is a waxy covering. It protects the animal and helps prevent evaporation of water. The exoskeleton doesn't grow so the arthropod has to occasionally shed this covering and grow a new larger exoskeleton. This process is called molting. It takes awhile for the new exoskeleton to get hard and protect the animal.
Examples of arthropods are:
Listed below is a cool slide show link and books for the kids to learn more about arthropods.
Scholastic Study Jams Slide Show