Watch This - Blood for Kids
This is a great, fun video about human blood from Science for Kids, it explains how blood works and what it does. It's fascinating for kids, and adults, alike.
Craft Idea - Blood in a Bottle
Follow this tutorial using various food items, to illustrate the various components that make up blood.
External Links to Check Out -
Avian Circulatory System website
Blood in Leeches Helps Saves Species article from Audubon