Since blood is a mixture, it is great Halloween tie-in to chemistry! I begin the lesson with a short video about separating blood. I have found several YouTube videos that show well what happens when a person donates blood to a blood bank.
Then I break out this easy recipe. The kids love to make it and although it includes red dye, I have never had any major incidents with any of it.
I have had students whose religious beliefs keeps them from participating in the lesson, but they are still able to answer the follow-up questions, as well as watch the informational videos about donating blood and the separation of it.