1. Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Cold case A game of darts . A teaching sequence from the Forensics unit of WikiedScience, the online 11-14 curriculum from upd8 Untrialled version 1.0 May 2008 This activity is at ‘beta’ stage, for trialling and evaluation purposes only. It may need some modifications to work fully in the classroom. Please look out for revised version 2.0, available from www.upd8.org.uk

2. Whose footprints? Considering the reliability of evidence. ELABORATE Spattering of blood Applying ideas about reliability in the context of blood spatter patterns. EXTEND Death of a Rockstar What is a cold case? ENGAGE Death of a Rockstar What makes evidence reliable? ELICIT A game of Darts Exploring a reliability analogy. EXPLORE EXPLAIN Reliability trust Checking understanding of reliability. EVALUATE 7E Learning cycle : Cold Case A game of Darts Creating a reliability checklist. Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original

3. Activity 1: Explore and explain 3 Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate OK. Let’s play darts and you’ll see what I mean… now try and hit the bulls-eye with one of your darts. I was away when we did reliability at college. Can you tell me what it means, and why it’s so important? ! I don’t get it. How does this darts game help explain reliability? So keep trying. And put crosses on the diagram to show where your darts land. Oh. That is difficult.

4. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 4 The darts game was my way of showing you how to make repeated measurements. You kept trying to hit the bulls-eye. The accuracy is how close your darts land near the bulls-eye, but the reliability is how closely grouped all your darts are. So when we measure things lots of times, if the measurements are very similar, it’s a reliable result? And that’s the believable result to present in court? Exactly. Of course you want an accurate and reliable result! Now, have a go at my quiz to check you understand OK.

5. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate Match one caption to each picture: 5 A B C D Not accurate or reliable 4 Accurate and reliable 3 Accurate, but not reliable 2 Reliable, but not accurate 1 Dr Sherl’s favourite quote: I n forensics – as in all science – the more reliable the results are, the more believable the evidence.

6. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 6 Right, I make that one 25 cm. Are we ready to tell Dr Sherl our results? Well, we’ve got our shoeprints. Let’s measure them.

7. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 7 Why? What’s wrong? Well, I’m not sure about your measurement methods.

8. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 8 You only took one measurement. Remember our darts game? Is your result reliable ? Hmm. I can’t deduce the shoe size from one result. I need to measure all the shoeprints. Exactly. And you need to measure more carefully, too. It’s difficult to measure the size and get a reliable result. Once I’ve got all these results what do I do? How do I make sure I get the perfect shoeprint measurement?

9. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 9

10. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 10 Forensic tests must have reliable results. Results are reliable if they are repeatable. This means that other people get the same result when they follow the same methods as you. That makes sense. If everyone takes measurements in the same way and gets the same results, the results are believable! The best way to make sure your results are reliable is to… … carefully take the measurement several times… … remove all the results that are nowhere near your target (outliers)… … take the average and there’s your reliable result!

11. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 11 Dragon, check out what Dr Sherl says. She’s talking about the darts again here. Well, that’s why the ‘more results the better’. Scientists are confident when most results are similar. They remove the results that look really odd. But what if we don’t know what value to expect? Scientists don’t always know what results they’ll get, so how do they know which results are the outliers to remove?

12. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 12 Dr Sherl wants us to make a reliability checklist. Help! • • • • • To get a reliable result, I must…

13. Activity 1: Explore and explain Untrialled Beta activity from the Forensics unit of the WikiedScience curriculum © Science UPD8 at www.upd8.org.uk This page may have been changed from the original Engage Elicit Explore Explain Elaborate Extend Evaluate 13 • Take my measurements carefully • Take as many measurements as possible • Remove outliers (odd, or anomalous results) • Calculate the mean (average) • Control other variables (eg use the same tools to make measurements). To get a reliable result, I must… OK. So now we know how to get reliable evidence. Let’s see those shoeprints again…