Activity Introduction

Quick summary: In this lesson, students will learn about bloodstains are analysed.

Learning intentions:

  • Students will understand what a bloodstain is
  • Students will understand how to analyse bloodstains.

21st century skills: 

CommunicatingCritical ThinkingEthical UnderstandingProblem FindingProblem SolvingTeam Work 

Australian Curriculum Mapping

Content descriptions: 

Year 10 Science

  • Scientific understanding, including models and theories, is contestable and is refined over time through a process of review by the scientific community (ACSHE191)
  • People use scientific knowledge to evaluate whether they accept claims, explanations or predictions, and advances in science can affect people’s lives, including generating new career opportunities (ACSHE194)

Syllabus outcomes: SC5-12ES, SC5-13ES

General capabilities: Literacy, Critical and Creative Thinking, Ethical Understanding

Relevant parts of Year 10 achievement standards: Students evaluate the validity and reliability of claims made in secondary sources with reference to currently held scientific views, the quality of the methodology and the evidence cited. They construct evidence-based arguments and select appropriate representations and text types to communicate science ideas for specific purposes.

Topic: STEM

This lesson is part of the wider unit of work: Real-life CSI – Secondary 

Time required: 65 mins.

Level of teacher scaffolding: High – there is likely to be quite a lot of explanation needed, as well as students requiring assistance during the practical part of the lesson.

Resources required:

These materials are per group. Suggested group size of two to three students.

Experiment 1: Release height

  • Graph paper
  • Measures: 30cm and 100cm rule
  • Newspaper
  • Pencil
  • Pipette or bottle with eye-dropper (something that will accurately deliver one drop of fluid with a consistent volume)
  • Plain paper (to make label sheets)
  • Stand and clamp – something to attach the pipette or bottle holding the synthetic blood.
  • Synthetic blood (see https://www.scribd.com/document/156835304/FSB06 for recipes).

Experiment 2: Impact surface

  • Graph paper
  • Pencil
  • Materials with different surfaces. E.g., cardboard, plastic bag, ceramic tile, carpet square, paper towel, wood, newspaper, metal, clothing (socks, jeans, T-shirt, etc.)
  • Measures: 30cm and 100cm ruler
  • Pipette or bottle with eyedropper
  • Stand and clamp
  • Synthetic blood (see https://www.scribd.com/document/156835304/FSB06 for recipes).

Experiment 3: Direction of travel

  • 30cm rulers
  • Pencils
  • Plain paper to make copies of:
    • Sheet A: A prepared sheet of bloodstains with information about how the bloodstains were created.
      • Dip a toothbrush in the simulated blood and fling droplets from the toothbrush as your arm moves across the paper in a definite direction, e.g. R→ L.
      • Label the paper with a general description of the action. E.g. R→ L direction, with the angle changing from shoulder to paper level.
    • Sheet B: A prepared sheet of bloodstains with NO information about how the bloodstains were created.
      • Dip the toothbrush in the simulated blood.
      • Place your elbow on the table, and, using a protractor, position your arm at a predetermined angle, eg 45 degrees.
      • Keeping the arm at the measured angle, fling droplets off the toothbrush as your arm moves across the paper, e.g. R→ L.
      • Do not provide a description of your actions, but make sure you record them for later.
  • Synthetic blood (see https://www.scribd.com/document/156835304/FSB06 for recipes).
  • Student Worksheets (one per group)
  • Toothbrush

Keywords: Forensic Science, Crime Scene Investigation, Evidence, Trace Evidence, Fingerprints, Impressions, Blood splatter, Kastle-Meyer Test, Hair, Science, STEM, STEAM, photography.

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian Curriculum.

Worksheets

Teacher Worksheet

Teacher Preparation

Learning intentions: Students will...

  • ... understand what a bloodstain is
  • ... understand how bloodstains are analysed.

Success criteria: Students can…

  • … explain what a bloodstain is
  • ... analyse bloodstains.

Teacher content information:

Blood and other bodily fluids, like saliva and skin cells left at a crime scene, can provide valuable information. They can be used to identify who was at the crime scene and what might have happened. They may also provide DNA evidence to analyse (explored further in the “Cracking the case with the code” lesson).

Even when the weather or perpetrators wash away evidence, field-based forensic scientists can detect traces of blood and other bodily fluids. Crime-scene investigators can treat areas they believe to contain traces of blood or other bodily fluids with a fluorescent chemical that is visible under ultraviolet light.

When a forensic team finds what they believe is blood, reagent tests, known as presumptiv

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Student Worksheet

Thought starter: It's a bloody mess in here!

1. Watch the following videos with more information on blood splatter analysis:


Bloodstain analysis - National Forensic Science Technology Centre (https://youtu.be/3jFKZaSeNjg)


Introduction to Forensic Science - 3.2.4 - Blood Spatter (https://youtu.be/42yZtlu3PJA)

Bloodstain Analysis

Adapted from ASISTM Forensic Investigations: Blood Analysis Experiments available from https://johnbowne.enschool.org/ourpages/auto/2016/3/3/43404396/bloodspatter%20complete%20activities.pdf

Experiment 1: The effect of release height on the diameter and shape of bloodstains.

You will be investigating the effect of release height on the diameter and shape of a bloodstain. As a group, read the method, identify your variables and come up with a valid aim and hypothesis for this experiment.

Independent variable (the one you are changing):

Dependent variable/s (the one/s you are measuring):

Controlled variables (the ones you are keeping the same):

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