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1. Science Ahead A Lower Secondary Science Course Science Ahead Stage 7

2. CHAPTER 2 Physical Quantities and Measurements Science Ahead Stage 7 What type of measurements do you need to make when you bake bread or cookies? What do you use to make the measurements?

3. Chapter 2 Physical Quantities and Measurements Science Ahead Stage 7 Use the appropriate units for length, area, volume, mass and time. Use the appropriate prefixes, milli-, centi- or kilo-, in relation to length, area, volume, mass and time. Use a measuring tape and metre rule to measure length. Calculate or estimate the areas of regular and irregular two-dimensional figures. Use suitable apparatus and methods to measure volume. Use an electronic balance to measure mass. Use a stopwatch or timer to measure time. What Will You Learn in This Chapter?

4. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

5. Science Ahead Stage 7 2.1 Why Do We Make Measurements? What is a qualitative observation? Which observation is often used in science? Why? At the end of this section, you should be able to answer the following questions: What is a quantitative observation?

6. Science Ahead Stage 7 2.1 Why Do We Make Measurements? Why do we use quantitative observations more often than qualitative observations?

7. Science Ahead Stage 7 2.1 Why Do We Make Measurements? We make measurements in our daily lives. Making measurements

8. Science Ahead Stage 7 2.1 Why Do We Make Measurements? Key Points Observations can be either qualitative or quantitative. Quantitative observations are often used in science because they are objective, accurate and can be clearly communicated. Quantitative observations are made using instruments according to standard procedures.

9. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

10. There is a square pond. Four trees are growing, one at each corner of the pond. The pond needs to be made bigger, so its AREA becomes twice as large, but it still needs to be a square. How can you make the pond bigger so that the four trees stay in the same place, at the corners of the pond, just like before? Remember: You cannot move or dig up the trees. They must stay where they are.

11. Science Ahead Stage 7 2.2 Physical Quantities and SI Units What are examples of physical quantities? What is an SI unit? At the end of this section, you should be able to answer the following questions: What are some commonly used prefixes in measurements?

12. Science Ahead Stage 7 2.2 Physical Quantities and SI Units A physical quantity is a physical property that can be measured using numbers. In the past, methods of measuring physical quantities were inaccurate and different units were used in different parts of the world. Measuring instruments used today

13. Science Ahead Stage 7 2.2 Physical Quantities and SI Units SI Since 1960, scientists from different parts of the world have agreed to adopt a single system of units. SI stands for Système International d’Unités in French . This system is used in science as it is the International standard for measurement.

14. Science Ahead Stage 7 2.2 Physical Quantities and SI Units Common physical quantities and their corresponding SI units Physical quantity SI unit Symbol for unit Length metre m Mass kilogram kg Time second s Temperature kelvin K Electric current ampere A Note that the name of a unit starts with a lowercase letter, even if the symbol uses the upper case.

15. Science Ahead Stage 7 2.2 Physical Quantities and SI Units What units are shown on the packaging of these products?

16. Science Ahead Stage 7 2.2 Physical Quantities and SI Units Prefix Symbol Meaning tera T 1 000 000 000 000 giga G 1 000 000 000 mega M 1 000 000 kilo k 1000 hecto h 100 deca da 10 deci d 0.1 centi c 0.01 milli m 0.001 micro μ 0.000001 nano N 0.000000001 pico p 0.000000000001

17. YouTube video: Powers of Ten https://www.youtube.com/watch?v=0fKBhvDjuy0

18. Science Ahead Stage 7 2.2 Physical Quantities and SI Units Key Points A physical quantity is a physical property that can be measured using numbers. The SI units are the standard units used worldwide. Prefixes, such as milli-, centi- and kilo-, are added to an SI unit to form smaller or bigger units.

19. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

20. Science Ahead Stage 7 2.3 How Do We Measure Length? Can you always rely on your sense of sight to make the correct observations? Which line, PQ or RS, is longer? Which circle in the centre, X or Y, has a larger diameter? Who is the tallest?

21. Science Ahead Stage 7 2.3 How Do We Measure Length? What is length? What is the SI unit of length? What do we use to measure length? At the end of this section, you should be able to answer the following questions: What is a parallax error?

22. Science Ahead Stage 7 2.3 How Do We Measure Length? Length is the distance between two points. The SI unit of length is the metre (m). What instruments can we use to measure length? A measuring tape, metre rule, or half-metre rule is used to measure length. A measuring tape is used to measure distances or lengths of up to about a hundred metres.

23. Science Ahead Stage 7 2.3 How Do We Measure Length? Can you name an occupation associated with these types of measuring tapes? Can you use these tapes to measure the thickness of a strand of hair accurately? We use a metre rule or half-metre rule to measure shorter distances, or lengths in centimetres. Like a measuring tape, the smallest division is 1 mm or 0.1 cm.

24. Science Ahead Stage 7 2.3 How Do We Measure Length? How to measure length correctly using a rule

25. Which one is correct?

26. Science Ahead Stage 7 2.3 How Do We Measure Length? Key Points Length is the distance between two points. The SI unit of length is the metre (m). We can measure length using a measuring tape, metre rule or half-metre rule. Parallax error is caused by placing the eye in the wrong position when reading a measurement. We can avoid it by placing our eye vertically above the mark on the scale to be read.

27. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

28. Science Ahead Stage 7 2.4 How Do We Measure Area? What is area? What is the SI unit of area? How do you calculate the area of a regular figure? At the end of this section, you should be able to answer the following questions: How do you estimate the area of an irregular figure?

29. Science Ahead Stage 7 2.4 How Do We Measure Area? Area is a measure of the extent of a figure. The SI unit of area is the square metre (m 2 ) . Other common units of area include the square millimetre (mm 2 ), square centimetre (cm 2 ) and square kilometre (km 2 ). One square metre (1 m 2 ) is the area of a square that measures 1 m on every side.

30. Science Ahead Stage 7 2.4 How Do We Measure Area? How do we find the area of a regular figure? A = l x l A = l x b A = b x h     A =πr 2

31. Science Ahead Stage 7 2.4 How Do We Measure Area? How do we find the area of an irregular figure? Divide the area of the irregular figure into small unit squares. Count the number of unit squares filled by the figure. An incomplete unit square is counted as one if at least half of it is filled. The approximate area is then calculated by multiplying the number of filled unit squares by the area of one unit square. 3 2 1

32. Science Ahead Stage 7 2.4 How Do We Measure Area? Using 1 cm 2 unit squares to estimate an irregular area

33. Science Ahead Stage 7 2.4 How Do We Measure Area? Key Points Area is a measure of the extent of a surface. The SI unit of area is the square metre (m 2 ). The area of a regular figure can be calculated using a formula. The area of an irregular figure can be estimated by counting the number of unit squares that are at least half-filled by the figure.

34. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

35. Science Ahead Stage 7 2.5 How Do We Measure Volume? What is volume? What is the SI unit of volume? How do you measure the volume of regularly-shaped objects? At the end of this section, you should be able to answer the following questions: How do you measure the volume of irregularly-shaped objects?

36. Science Ahead Stage 7 2.5 How Do We Measure Volume? Volume is the amount of space occupied by a substance or an object. The SI unit of volume is the cubic metre (m 3 ). Smaller units include the cubic centimetre (cm 3 ), cubic millimetre (mm 3 ), litre ( l ) and millilitre(m l ). One litre ( l ) is equal to 1000 millilitre (m l ) and is equivalent to 1 cubic centimetre (cm 3 ).

37. Science Ahead Stage 7 2.5 How Do We Measure Volume? How do we find the volume of a regularly-shaped object? V = l 3 V = πr 2 h V = lbh    

38. Science Ahead Stage 7 2.5 How Do We Measure Volume? How do we find the volume of a liquid?

39. Science Ahead Stage 7 2.5 How Do We Measure Volume? How to take a reading from a measuring cylinder The curved surface of the water is called the meniscus .

40. Science Ahead Stage 7 2.5 How Do We Measure Volume? Some objects, such as pebbles, seashells and keys, have irregular shapes. We can find the volumes of these small objects by using the displacement method . How do we find the volume of an irregularly-shaped object?

41. Science Ahead Stage 7 2.5 How Do We Measure Volume? What is the volume of the pebble?

42. Science Ahead Stage 7 2.5 How Do We Measure Volume? Key Points Volume is the amount of space occupied by a substance or an object. The SI unit of volume is the cubic metre (m 3 ). The volume of regularly-shaped objects can be calculated using a formula. The volume of a liquid can be measured using a volumetric flask, measuring cylinder, burette or pipette. The volume of a small irregularly-shaped object can be found by using the displacement method.

43. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 Chapter 2 Physical Quantities and Measurements

44. Science Ahead Stage 7 2.6 How Do We Measure Mass? What is mass? What is the SI unit of mass? At the end of this section, you should be able to answer the following questions: How can you measure mass?

45. Science Ahead Stage 7 2.6 How Do We Measure Mass?   1 apple 100 g 1 grain of rice 0.02 mg An adult male elephant 6000 kg

46. Science Ahead Stage 7 2.6 How Do We Measure Mass? Compare the two types of balances. What are the advantages and disadvantages of using each type?

47. Science Ahead Stage 7 2.6 How Do We Measure Mass? Key Points Mass is the amount of matter in a substance. The SI unit of mass is the kilogram (kg). Mass can be measured using a beam balance or an electronic balance.

48. 2.1 Why Do We Make Measurements? 2.2 Physical Quantities and SI Units 2 .3 How Do We Measure Length? 2.4 How Do We Measure Area? 2.5 How Do We Measure Volume? 2.6 How Do We Measure Mass? 2.7 How Do We Measure Time? Science Ahead Stage 7 2.7 How Do We Measure Time?

49. Science Ahead Stage 7 2.7 How Do We Measure Time? What is time? What is the SI unit of time? At the end of this section, you should be able to answer the following questions: What is commonly used for measuring short periods of time?

50. Science Ahead Stage 7 2.7 How Do We Measure Time? The SI unit of time is the second (s) . Other units of time include the minute (min), hour (h), day, month, year, decade, century and millennium.

51. Science Ahead Stage 7 2.7 How Do We Measure Time? On what occasions is measuring time interval useful? Stopwatches and timers are commonly used in the laboratory. A mechanical stopwatch has a minute hand and a second hand. An electronic stopwatch has a digital display.

52. Science Ahead Stage 7 2.7 How Do We Measure Time? Key Points The SI unit of time is the second (s). Stopwatches and timers are commonly used for measuring short periods of time or time intervals in the laboratory.

53. Science Ahead Stage 7 Chapter review and extension Reflection (Workbook page 22) Review Questions (Student Book page 40–41) Revision Worksheet 2 (Workbook pages 23–24) Think-tank (Student Book page 42) Chapter 2 Physical Quantities and Measurements

54. Watch at HOME: Units Of Measurement | Why Measurements Matter? | The Dr Binocs Show | Peekaboo Kidz https://www.youtube.com/watch?v=AVC-426M6V0

55. Science Ahead Stage 7 Acknowledgements Slide 2, concept image of the baking © Lily Oh/123rf.com Slide 7, contractor working on laminate wooden floor © Elnur Amikishiyev/123rf.com; boy with thermometer in mouth, lying in bed © Moodboard/123rf.com; scientists in gloves measuring weight of blue bulk solid © scanrail/123rf.com Slides 7 and 81, hand holding stopwatch © Wasan Gredpree/123rf.com Slide 7, Slide 11, kitchen scale © Kirill Kirsanov/123rf.com Slide 11, graduated cylinder © serezniy/123rf.com; digital clinical thermometer © mrgao/123rf.com Slides 11 and 47, electronic sport timer © belchonock/123rf.com Slide 14, box of Golden Grahams wheat cereal © komienko/123rf.com; Schweppes © Vladimir Nenov/123rf.com; multi-Purpose Cling Film © James McDowall/123rf.com Slide 20, constructor worker with a measuring tape © Dinish Tolipov/123rf.com; line committee measure distance on javelin throw © Manit Larpluechai/123rf.com Slide 21, tape measure © Rapeephat Chirapanyanon/123rf.com; rolled measuring tape © Valerii Zan/123rf.com; metre rule and half-metre © MCE/MCE Slide 35, apparatus for measuring volume, © MCE/MCE Slide 42, white long-grain rice in wooden bowl © Svetlana Kuznetsova/123rf.com; red apple © Todd Kuhns/123rf.com; big elephant in national park © byrdyak/123rf.com Slide 43, triple beam balance scale © Sarah Greenwood/Wikipedia.com; laboratory high precision weighing scale © Warut Sintapanon/123rf.com; empty shelf on a wooden wall © donatas1205/123rf.com Slide 47, black plastic alarm clock with red display © pixelrobot/123rf.com; hourglass © Burmakin Andrey/123rf.com; old sundial in a garden © Colin Moore/123rf.com; old grandfather clock © Howard Brian Klaaste/123rf.com; luxury watch © Oleksandr Moroz/123rf.com Slide 48, chess clock and board with chess pieces © lightfieldstudios/123rf.com; electric oven © Piotr Pawinski/123rf.com; stopwatch © Kirill Cherezov/123rf.com