Science4Fun
Science4 Fun: Blood
What is blood? Discover how and why blood travels in the body, the three main types of blood cells, and the different blood types.
Exploratorium
Exploratorium: Microscope Imaging Station: Cell Motility
This interesting site explains how cells move and provides videos depicting the movement of various human and animal cells.
BBC
Bbc: Gcse Bitesize: The Challenges of Size in Animals
This lesson focuses on blood including it's functions including transporting materials around the body and protecting against disease. It explains the components of blood and the functions of each and offers a link to an assessment.