I've recently received an assignment, asking several questions, including:

Why does blood turn brown, and what chemical reactions are involved with this change?
Do different fibres (i.e. carpet) change the blood in any way (like its composition)?
What do different fibres do to blood, and what is their effect at a crime scene?

Please see the sticky at the top of this forum. There is a load of info on the WEB for you to do your own research. Please don't ask or expect us to do your assignment for you. If you want use to confirm, or clarify info you found, we can do that.