Biscuit Investigation

1. Biscuit Investigation D. Crowley, 2008

2. Biscuit Investigation • Your task is to investigate why a Jaffa Cake is a ‘cake’ and a ginger nutbiscuit is a biscuit • As you complete this experiment you need to think how you can identify how the two types of food can be classified, whilst making this test you can make this test a fair one, how you can be accurate and precise, and how you can ensure the results are reliable

3. Initial Questions • Initially you need to brainstorm what differences there are between a Jaffa Cake and a ginger nut biscuit • What are they made of • What textures do they have • Do they have layers • How are they made • What happens when the biscuits are wet / dry etc… • Think about what experiments you could do to highlight the difference between a cake and a biscuit

4. Importance • McVities recently proved that Jaffa Cakes are indeed cakes (they baked a huge Jaffa Cake to prove this) • The difference is important for tax reasons as: - • Cakes do not attract VAT • The alternative classification would be a chocolate covered biscuit which is classed as a luxury food item, attracting VAT

5. Key Words • During your investigation you will come across some key words: - • Accurate: a measurement that is close to the true value (accuracy can be increased by controlling the key variables) • Precision: this is a more precise measurement, which can be achieved by using a smaller scale • Reliability: the experiment needs to be repeatable – if someone else did the experiment then they should get exactly the same results: this comes from repeating your experiment

6. Key Words • During your investigation you will come across some key words: - • Dependent variable – what is changed by the experiment (what you are going to measure) • Independent variable – what you change • Control variable(s) – what you are going to keep the same, making the experiment more accurate

7. Demo • Look at the two biscuits closely – what experiments are possible to identify the differences between a cake and a biscuit • Determine which factor(s) you could test for - what is your independent variable (what you change), and what is your dependent variable (changed by the experiment) • What control variables will you have to monitor?

8. Introduction • Initially write you introduction for the biscuit investigation • Note your aim (what we are doing); why we are doing it and what tests which will carry out and why • What makes a Jaffa Cake a cake, and not a biscuit: – • How moist is the cake • Is it layered • How hard / soft is it • How much air is within it • What are they made of • What textures do they have • Do they have layers • How are they made • What happens when the biscuits are wet / dry…

9. Stale • The difference which McVities used to prove that Jaffa Cakes are indeed cakes is that:- • Cakes go hard when they are stale • Biscuits go soft when they are stale • Jaffa Cakes go hard, therefore McVities successfully claimed that they are cakes (they baked a huge Jaffa cake to prove the point) • Why is there a difference between a cake and biscuit – what causes one to go hard when stale, and the other to go soft?

10. Moisture • Moisture loss / gain is the difference: – • A biscuit goes hard when stale, as it is losing moisture from within the biscuit • A cake goes soft when stale, as it is gaining moisture from the surroundings • Your task is to therefore devise an experiment to prove that the difference between a cake and a biscuit is due to the ability to gain or lose moisture

11. Method • Your task is to now consider what methods you are going to use to measure the moisture changes between a biscuit and a cake • How are you going to make your experiment: - • Accurate (as close to the true value as possible) • Reliable (so someone else can repeat this experiment and get similar results) • Precise (how many readings are going to be taken and how can you ensure each repeat is completed in the same way) • Complete a step-by-step guide to completing your experiment • Note your independent variable (thing you change) and how you will change this; and your dependent variable(s), and how you will measure this • What data are you collecting / recording

12. Method - Moisture • In order to measure moisture variations we could do a variety of experiments: - • Using a moisture sensor identify the levels of moisture in the biscuit and the cake over time • Measure how ‘crumbly’ the biscuit and cake are over time • Measure the mass of the biscuit and cake, and then measure their mass after a given amount of time

13. Prediction • What do you expect will happen when you change the independent variable • Can you explain what will happen, and why you think this • E.g. I think that when I change the… the… will… because… • We should find a difference in both the absorbency and strength of the different brands of paper towel • This difference will probably be due to the different composition of each paper towel (what it is made from); how thick each sheet is; how the sheet is actually constructed etc…

14. Apparatus Order Form • Finally, you will need to order all the apparatus your require to carry out this experiment • Ensure you have thought of everything, and just as importantly you must identify how much equipment you need – e.g. 1 x scales; 3x biscuits etc… • Your apparatus form must be signed off before it will be given to the laboratory technicians

15. Results - Moisture

16. Experiment • You have the first 20 minutes of the next 3 lessons to complete your experiment • Remember to be as accurate and precise as possible when collecting your results • The whole class will be carrying out the same experiment, so repeats will not be necessary for the biscuits

17. *Mini Task • Once you have set up your experiment you have a mini-assignment to complete: - • Using the nutritional information given you need to design a poster explaining to someone in the street which is the ‘healthiest’ choice to eat between the Jaffa Cake and the ginger nut • You will have the remainder of this lesson, plus the remainder of the next lesson (once you have collected your day 2 results) to complete this poster

18. *Jaffa Cake – Nutritional Information

19. *Ginger Nut – Nutritional Information

20. Conclusion • Your task is to graph your results for the change in mass over time of the Jaffa Cake and the ginger nut • A scatter graph is most suitable – time on the x axis, and mass of the biscuit on the y axis • Remember to add a title; units etc… • Once you have drawn your graphs you need to complete an analysis – what do the results show you / why do you think this is?

21. Graph • Hopefully you have found the mass of the Jaffa Cake decreased (as it becomes hard when it goes stale); and the mass of the ginger nut increased (as it becomes soft when it goes stale)

22. Evaluation • Finally you need to complete an evaluation – were there any anomalous results? • What errors may have caused these: - • Random error (happens occasionally) • Systematic error (same mistake occurred every time (likely due to you measuring this incorrectly) • How accurate was your experiment – did you consistently get the same results? • Was your method fair allowing you to collect accurate results? • Do you have enough reliable evidence to support the conclusion that you have made • What improvements would you do if you could repeat this experiment?

23. History • Marie Antoinette was beheaded during the French revolution - a period of time when most people had very little to eat • Marie Antoinette is supposed to have told the starving rebelling masses of people that, if they can’t eat bread they should, ‘eat cake’ • Use what you have found out about ‘cake’ and ‘biscuit’ to comment scientifically on what Marie Antoinette said • Cake and bread both go hard when they are stale – so bread could be classified as a cake (so the starving rebelling masses were already searching for cake)!