To make blood, you need corn syrup (plasma), red hot candies (red blood cells), lentils (platelets), and white beans (white blood cells). Have fun mixing the ingredients together and try not to eat too many read hots (Please see the try before you buy Life Science Guide for more detailed instructions and printable lab sheets).
We talked about what each item represented, and O(6) was VERY skeptical that the liquid part of the blood is clear. However, when she poured the red hot candies into the mixture, a light bulb went off and she said "Oh! Now I understand why blood is red!"
I realized that E(3) was really paying attention to the lesson, when her thumb was bleeding and she sadly said "I don't have ANY platelets. I just don't have any platelets!" She thought that since she was bleeding, and it wasn't scabbing over quickly, she didn't have any platelets!
You can check out this curriculum to "try it before you buy" here.