This is a fun way for students to learn how the blood circulates through the heart, while using their bodies, and running around! Set up a heart using students as the walls, atriums, ventricles, and valves. They should hold hands, or touch hands- except the people representing the valves-they will open and close as the "Blood" people pass through.Select 2 students to be the "blood". Set up a chair on each side of the "heart" to represent the lungs-or you could use students.Place a red object or paper at each lung-this represents an oxygen molecule that is picked up by the "blood". The "blood" will travel through the atriums to the ventricles ( you can have the atrium students gently "squeeze" the blood people through the valves- which will open and close their outstretched arms. Show oxygenation of the blood by picking up the red object at the lungs, traveling through the heart, and picking up the blue object to show de-oxygenation and use of oxygen by the body. You might have to take several runs-students will want a chance to be the "blood"! You may want to use a 2 chambered heart for younger students. ** Remember blood is never blue-just purple-red - and it doesn't turn red when exposed to air. Have fun!