One way I have helped getting the idea from ounces to cc's 30 cc equals one ounce. So what I will do is take either trauma dressings or abd pads get 1 liter of water and put red food dye into the water. Then I will have the students take the dressings and try to soak up the colored water. It helps them to get the idea of fluid loss and also to get familar with the differant types of dressing out there. Hope this helps!
First ask someone to volunteer and give them some paper towel or a rag. Take a small coffee cup or similar and fill it with a colored liquid and dump it on the floor. See how much of a mess it makes.
Please remember that the viscosity of blood is not the same as water and other fluids. Blood is thicker than water and does not expand as such.
Go to the local blood and ask if they have some out of date units of blood. If allowed to obtain, then see how much blood each container has (each organization is different) and then spill on controlled flooring (bio-hazard).
One has to remember that water or mixed with blood appears worse as well, and have to make allowances.
And would like to add: Just as the viscosity of blood differs to that of other fluids, the same principal applies whereby density of the surface onto which the blood falls also vary. For example: Beach sand vs a solid tiled floor, hence adding another variable into the eqaution.