Materials Required:
Lentils (to represent blood)
Water
Yellow food coloring
Clothes rack
Two empty water bottles (with ends cut off)
Colander
Yogurt container
Funnel
Plastic bag
Straw
Tape
Steps Involved:
Mix lentils with water and yellow food coloring to represent the blood.
Set up the clothes rack as the frame for the model.
Attach the cut ends of the water bottles to the rack to represent the arteries carrying urea from the liver to the kidneys.
Represent the three parts of the kidneys (Cortex, Medulla, Pelvis) using the colander, yogurt container (with holes for filtering), and funnel respectively.
Tape a plastic bag to the bottom of the funnel to act as the bladder.
Insert a straw through the bottom of the plastic bag and tape it into place to represent the urethra.
Pinch the straw at two places to simulate the internal and external sphincters.
Pour the urea mixture into the kidneys and observe how it collects in the bladder.
Release the sphincters to let the bladder empty into the potty.
Collect lentils from the Cortex and Medulla (colander and yogurt sieve) to use in other activities.
English 
Portuguese