Effect of Height and Surface Texture on Blood Spatter Name PART ONE Directions: 1. Spread newspaper on the floor of your work area 2. You will prepare one ½ sheet of paper for each height used. 3. Label the card with the height on the corner of the paper 4. Use a meter stick to determine the height of the dropper bottle 5. With the help of your partners, hold your stick vertically for measurement, squeeze ONE drop of blood from a height of 25 cm. Hold your hand steady and aim for one side of the card 6. Repeat the process for another drop 7. Repeat the process for the different heights. Data Table: Effect of Height on Diameter of Blood Drop Height of drop Diameter of drop 1 Diameter of drop 2 25 Average diameter Sketch one of the drops 50 100 150 200 250 On the graph below, plot the points for Average height to drop diameter (mm) below. Connect your dots.
Questions: 1. Is there a relationship between the height from which the blood is dropped and the size of the blood-spatter droplets? Support your answer with data. 2. True or False: As the height from which the blood is dropped increases, the size of the blood spatter continues to increase. Support your answer with data. 3. Blood is dropped from heights of 25 cm and 250 cm. Compare and contrast the outer edges of blood droplets produced from these two heights. 4. Examine the blood spatter produced by dropping blood from the six different heights. Is there a relationship between the height from which the blood is dropped and the number of satellites produced? Support your answer with data. 5. Compare your results with your classmates. a. Were your results similar to those of your classmates? If not, how did they differ? b. If someone accidentally dropped two or more drops of blood in the same location, what effect would it have on the blood-spatter pattern? 6. Given the diameters of blood drops below, estimate the height that the drop came from (use your graph to help) a. 8 mmb. 14 mmc. 12 mm-
PART TWO 1. Place the medium on the ground (plastic bag, paper, etc) 2. Using a meter stick measure 30 cm above the ground 3. With the help of your group members, drop ONE drop of blood onto the medium 4. Repeat the process for the rest of the mediums. 5. Fill in the table below Medium Description Sketch Computer paper Cardboard Paper Bag Plastic Bag Ziplock Back Fabric 1. Why is it important to look at the surface that the blood was dropped on? 2. How did the drops compare on smooth surfaces vs. rough surfaces? 3. Why would it be hard to analyze spines on a drop that landed on fabric?
ACTIVITY 8-3 BLOOD-SPATTER ANALYSIS: EFFECT OF HEIGHT ON BLOOD DROPS Teacher Notes Teaching Tip: Recipe for simulated blood: Red food coloring, glycerin, and water or Karo syrup, red food coloring, and water Dispense by way of small polyethylene dropping bottles Notes: 1. Have student teams of four divide into pairs for measuring the heights for the blood drops. One group of two students could do measurements of 25, 50, and 100 cm, and the other pair within the group can measure the heights of 150, 200, and 250 cm. 2. Dispense one to three drops from various heights: 25, 50, 100, 150, 200, and 250 cm. 3. Use separate cards if necessary. 4. Label cards before dropping blood on them. 5. Use lots of newspaper, otherwise the floor will be stained. 6. Have each team designate at least one team member to oversee that drops are dispensed from the correct height. 7. Do not rush students; provide extra 5 x 8 cards as necessary. 8. Droplets of simulated blood will probably not dry for several days, so do not stack the spatter cards. Questions: 1. Is there a relationship between the height from which the blood is dropped and the size of the bloodspatter droplets? Support your answer with data. Yes 2. True or False: As the height from which the blood is dropped increases, the size of the blood spatter continues to increase. Support your answer with data. True 3. Blood is dropped from heights of 25 cm and 250 cm. Compare and contrast the outer edges of blood droplets produced from these two heights. The outer edges of the blood dropped from 250 cm will have more satellites. 4. Examine the blood spatter produced by dropping blood from the six different heights. Is there a relationship between the height from which the blood is dropped and the number of satellites produced? Support your answer with data. Yes 5. Compare your results with your classmates. a. Were your results similar to those of your classmates? If not, how did they differ? Answers will vary. b. If someone accidentally dropped two or more drops of blood in the same location, what effect would it have on the blood-spatter pattern? The second drop might mask the pattern of the first one.