I would like to create a tabletop activity where I can demonstrate coagulation. I wouldn't like to use kids/parents blood, therefore I am trying to look for an alternative. I was thinking on using milk and vinegar to make curds, but still is not enough for my own vision. If anyone has any ideas or example let me know!
Liz, here is a very easy and scientific idea how to ilustrate the blood coagulation process. Take a microscope slide and add a blood drop from fourth finger of left hand. Using a stopwatch start to count the time for blood to coagulate. You can follow the process by checking time after time the blood clot formation by means of a toothpick. When blood start to clot, filaments of fibrin are formed. So when you mix the blood drop by toothpick, filaments of blood can be pulled up. All the proces takes few minutes, so each kid can try to measure his own blood clot time and even compare with other classmates. Try and I think you'll like it.
Since you are thinking about making curds, why not carry on and turn it into mozzarella cheese? You get enzymes (rennet) protein coagulation, cross linking, co-factors (vitamin C). The problem with this is there are no cells or platelets involved, so you can' to over the surface effects of coagulation. Here's a recipe that is pretty easy. You have to follow the recipe precisely, and everyone gets to get messy and eat some nice cheese after. http://www.channel4.com/explore/jamie-and-jimmy-friday-night-feast/cheese-maker.pdf
Cool suggestions above.
Here's what we did for Swiss children's TV. It was explained that there are various forms of coagulation: one can be illustrated by heat, the other by enzymes.
The heat experiment involves boiling of an egg in water. Initially the yolk and egg white are liquid. In boiling water by "coagulation" they turn solid.
To illustrate the biochemical side the cheese experiment is great.
Illustrating function of blood platelets I find more complex. We did not do this for the TV show in question. One could think of double sided tape (sticking on both sides, as in poster tape). You can let fine sand run through a tube or dwon a funnel or something. In the beginning as in a normal blood vessel the sand will run through. When there is a lesion, symbolized by the tape, sand will stick to the tape. This can be explained is the initiator of coagulation, that would make the rest of the sand sticky/coagulate as in the experiments explaiend above... Maybe one could elaborate something with dry ice that would make a fluid passing by turn into ice... just ideas.
Dry ice is always fun.
PS: I once used a really cool cartoon from the fun people at Birdo in Brazil to illustrate coagulation for adults. The cartoon is cult and the sounds lots of fun. Will work for kids.
http://www.youtube.com/watch?v=9QVTHDM90io
Do ask them in advance for their permission.: www.birdo.com.br or
To demonstrate what platelets do, I took a motorcycle radiator put water in it. then poked a few small holes with a nail. water starts leaking. Poor in radiator sealant and the holes plug. This shows how platelets work. Then I took a crow bar and made a 2 cm x 1/2 cm hole in the radiator. Poor water in, it leaks , put sealant in, it keeps on leaking because the hole is too big. I also used this teaching in medical school! It really sinks in!
My students see platelets as radiator sealant, if you take a shot gun and put a hole in a radiator, no matter how much sealant you put in, it will not close the hole. It needs mechanical correction, in humans = surgery!
I like your milk and vinegar idea. I would just add some red food color to the milk in order to make it look like blood. It will be a very safe alternative. Lemme know what you think/ what you decide to do.
How do you think if bovine blood or plasma can be a safe alternative for demonstration purposes?
Thank you all for the comments! I might try the milk, vinegar (with food coloring idea from Akul) as the tabletop activity.
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