YEAR 8 SCIENCE 2012

1. YEAR 8 SCIENCE 2012 Mrs Sammut TERM 1

2. Some Golden Rules for MrsSammut’s Year 8 Science class. • 1. Move about the lab or class room in a safe manner. • 2. Always follow instructions from Mrs Sammut or MrsDevic • 3 .No laptops are to be opened until you are instructed to open them. • 4. We must always show respect to each other by not talking while others are talking • 5. All hair must be tied back. There no exceptionsbecause it is a fire risk! • 6. Always wear safety glasses and a lab coat for every pracclass unless otherwise instructed.

3. 7. Do not eat, taste, drink or sniff anything in the lab. It can be a health hazard! • 8. Always tell me or MrsDevic if you break something. • 9.Always seek clarification if you are unsure of anything. • 10. If we are using a Bunsen Burner have it on the visible yellow safety flame. • 11. Always use matches to light the Bunsen burner and always use tongs to pick up objects because they maybe hot or contaminated.

4. Year 8 Science Pearson Science Year 8

5. What is Science? • Science is all about asking questions, testing, asking more questions and doing more tests. • Science is a way of finding out how or why things happen.

6. What do scientists do? • The world around us is a fascinating, and sometimes confusing place, in which many mysterious things seem to happen. Albert Einstein said that the job of scientists was to take our experiences of this fascinating and confusing world and try to fit them into some logical system.

7. Chapter 1 – Working with scientific data • After completing this chapter you will understand the following….. • What is meant be the terms “first-hand” and” second- hand” data. • How to collect and analyse data in a variety of situations • Ways of presenting data • How to design an experiment

8. What is the difference between an mistake and an error? • Why scientists' take multiple measurements? • How do we use different technologies to access information? • What are the best tools to represent data collection in practical's?

9. Pre - Quiz • 1. Describe a time when you have worked successfully in a team. • 2. Explain what a fair test is? • 3. Explain the benefits of internet research. • 4. Identify what type of science skills you are good at. • 5. Explain why scientific research requires multiple investigations and experiments and why something is not proven from one experiment.

10. Glossary • Average qualitative data • Data quantitative data • Errors reading error • First-hand data second-hand data • Instrument error tare • Mean zero error • Mistakes • Parallax error

11. Can you please suggest why or how mistakes might occur while performing experiments?

12. Data • Data is the term given to all the observations and measurements that can be used to describe something. • Examples could include any of the following your height, weight, your hair, skin or eye color.

13. Types of data - Quantitative • Much of the data you find will be measurements that are written as numbers with units attached. • This type of data is known as quantitative data. • Therefore any data that is written in numerical form is referred to as quantitative data.

14. Types of data - Qualitative • Any data that can only be described in words is referred to as qualitative. • Therefore you need to remember when data is described in words its qualitative.

15. Types of Data – First-hand data • First hand data is collected from experiments. Generally when you conduct an experiment all the data that is collected is referred to as first-hand data.

16. Second-hand data • Second-hand data comes from other sources such as the internet.

17. Summary • First hand data – collected directly from the experiment that you or your practical team personally find out by running your own experiment. Any measurements that you take are first – hand data. • Second hand data – collected from sources such as the internet. The data comes from work of other people. It can be found in text books, newspapers, magazines, TV etc. ?Second hand data could also be obtained by interviewing experts.

18. Collecting your own data • What is first-hand data? • What is second hand data?

19. Mistakes • You can generally trust first-hand data since you collected it yourself from experiments that you ran. If the data is wrong, then its probably because you made a mistake. • Mistakes – are things that can be avoided if you take a little more care. Mistakes can happen when you spill material, use the wrong equipment, or follow the incorrect procedure. All these are obvious mistakes since all are careless and can be easily avoided.

20. Errors • Errors are not mistakes. • They are small and unavoidable variations that naturally occur in measurements. • Errors will always happen no matter how careful you are. This means that nothing is exact – even ‘accurate’ measurements have small variations and errors in them.

21. Parallax errors: Your eye can never be exactly over the marking of a measuring device. Everyone looks at markings at slightly different angles so everyone will take slightly different readings.

22. Reading errors • • Reading errors: Measurements often fall between the markings of a measuring device. Some estimation is required for you to take your measurement accurately.

23. Instrument errors: • Sometimes the instrument you are using is faulty and will never give the right reading. Some instruments give correct readings only at certain temperatures and will give small errors if used at any other temperature. A metal ruler expands when hot, pushing its markings further apart. This makes measurements taken on a hot day slightly smaller than those made on a cold day.

25. Lines on a ruler • Activity: Please take out a ruler. Can you suggest reasons for the different ways rulers are labelled? Why are different materials used for rulers?

26. Human reflex • • Human reflex: A stopwatch normally reads to one hundredth of a second (0.01 s). Humans are not as accurate as this: they simply can’t react quickly enough. • Measurements of time will vary between people because we all have different reflex times.

27. Zero errors • An instrument such as a beam balance or electronic balance should read zero when nothing is placed on it. • If it doesn’t read zero, then everything you measure will be a little out and all measurements will have a zero error.

28. Tare • When you tare an electronic balance, you are re-setting it to read zero when something like a beaker is placed on it. • You can then add material without having to worry about the mass of the beaker since it has already been subtracted from the total mass.

29. Repeatedmeasurements • Because errors always exist, people can measure the same thing differently. So, who has taken the ‘correct’ measurement? They all have. Unless someone makes a silly mistake there is no wrong answer. • Repeating measurements is a good way of improving accuracy. Once a collection of different measurements is taken, an average or mean (called the mean in maths) can be obtained.

30. To find an average: 1. Add all the measurements together. 2. Divide by how many measurements were taken.

31. The length of a mouse’s tail was measured by the various members of a group as: • • Su-Lin 8.1 cm • • Justin 8.4 cm • • Nicole 8.2 cm • • Hayden 12.9 cm • • Millai 8.5 cm • Hayden’s result can be ignored since his result is too far away from the rest of the group’s results. It looks like he made a mistake. • To obtain the most accurate measurement, it is best to average the other four results: • 8.1 + 8.4 + 8.2 + 8.5 = 33.2 • Four ‘good’ results were taken, so the average will be: • 33.2 = 8.3 cm

32. The mouse tail measured above averaged 8.3 cm, even though no one actually measured it as that. The mouse tail could be said to be between 8.1 and 8.5 cm. This could be written as 8.3 cm ‘give or take’ 0.2 cm, or 8.3 ± 0.2 cm.

33. A little give and take • It is often useful to write measurements with an estimation of how big the error might be. We allow a little ‘give and take’ by showing the error as ± (standing for ‘plus or minus’). • The exact measurement shown in Figure 1.2.5 needs a little guesswork. • Although it looks like it should be about 27°C, it could be a little higher or lower, perhaps as much as 1°C. The measurement could be written as 27°C ‘give or take’ 1°C. Scientists write this as 27 ± 1°C.

34. Science 4 fun inquiry Internet reaction times • How fast can you react? • Do this • 1. Use the key words reflex tester or reaction time in your internet search engine to find interactive games that will measure your reaction times. • 2. Although most of the games involve detecting a change in color of the webpage, some shoot tranquillizer darts into sheep while in others you play baseball! Try as many as you can to determine your average reaction time. • Record this. • Describe what happened. • Explain why you think this happened.

35. Activity – Ready, set, go! • Purpose: To identify human reflex errors and reinforce the need for repetition.

36. Calculating averages. • 1. Monday’s highest temperature was 15oC, Tuesday’s was 17oC, Wednesday’s was 21oC, Thursday’s was 16oC, Friday’s was 19oC. What was the average highest temperature for the five days?

37. Evaluation: • Please write ten sentences beginning with ‘I have learnt……’ about what you have learnt from this chapter.

38. Unit review – must be completed. • Please complete questions 1 - 17

39. Practical activities • Reaction times • Please read page 9 from your text book together as a class. Complete the activity.

40. Chapter 1.2 • You can not always run your own experiments or take your own observations and data. • Many experiments require equipment that is not available at school because of its expense, size and maintenance requirements.

41. If we wanted to find out what year the telephone was first working in Australia where would you go? • If you wanted to find images of a Trilobite ( a fossil), where would you go? • Now imagine you have no internet access or computer access. Where would you go to for the above 2 questions.

42. What are the problems you might find in searching for your answers on the internet? • What are the problems you might find in searching for you answers in a book?

43. What you learn during science is a summarised version of science and is expressed in a way that you will understand. • Unfortunately we are unable to cover the most recent research and discoveries because they are often to complex for us to understand. • Experiments take far more time than we have available during our classes in Year 8.

44. For instance genetic diseases pass from generation to generation and so studying the inheritance of them will take generations to do properly. • So therefore, if you are unable to run your own experiments, then you need to turn to second hand data. • Do we remember how we defined second-hand data? Where can we find it?

45. Improving second-hand data • Second-hand data is easy to find but it is not always accurate. • Simple checks can ensure that the data you find can be trusted. • Some data never changes, for example; ice melts at 00C at sea level and will always do so.

46. Other data quickly becomes out of date and will not accurately describe what is happening right now. • For example climate change is happening much quicker than scientists first thought. So therefore we must ensure that the information that we use is the most recent as possible.

47. Homework • Ask your parents or grandparents how they communicated without the internet. • What did they do without mobile phones or the internet? • How did they contact family and friends? • What was it like before there were telephones in houses? Please reflect on how ‘convenient’ the internet has become and also how much we rely on it.

48. You are able to check how old data is by finding the imprint page of the book or magazine. • This page can usually be found in the first few pages of any book, magazine or journal. • Websites should have the date they were created and last updated at the bottom of their opening pages.

49. Can it be trusted? • Encyclopedias, scientific journals and science textbooks can usually be trusted to provide accurate data. • Ensure you check the date! • Data can also be trusted if it comes from respected scientific magazines such as New Scientist, COSMOS, American and National geographic.

50. Gossip and celebrity magazines cannot be relied on to provide accurate data and information.