The respiratory system

How your body works
http://kidshealth.org/kid/htbw/htbw_main_page.html

How does your body digest different foods ?
http://interactivehuman.blogspot.com.es/2008/05/digestion-interactive-game-for-kids.html

the skeletal system

the circulatory song

the cardiovascular system

The excretory system

How does  the respiratory system work?

How the digestion is produced.

teeth and eating quiz
http://www.bbc.co.uk/schools/scienceclips/ages/7_8/teeth_eating.shtml

Skeletons and muscles 

http://www.bbc.co.uk/bitesize/ks2/science/living_things/skeletons_muscles/play/

Keeping healthy quiz

http://www.bbc.co.uk/schools/scienceclips/ages/9_10/keeping_healthy.shtml