4 B
Dr Lee Yeung Chung, Dr Kwok Ping Wai, Dr Yip Wai Lin & Dr Cheng Nga Yee
Preface New Science is written in accordance with the 2024 Science (Primary 1–6) Curriculum Framework 6) Curriculum Framework . This series encourages pupils to explore with curiosity and learn through applying. It aims at nurturing pupils’ curiosity and interest in science, helping them acquire basic scientific knowledge, and cultivating their creativity and innovative thinking to better prepare them for the future. It features: 1 A systematic course structure This series organises the essential learning content stated in the curriculum framework into different units. It allows pupils to gradually build basic scientific knowledge and skills of the four learning strands across grades, develop science inquiry and problem-solving skills, learn about innovative technology, and develop preliminary engineering thinking and practical skills. 2 A close connection with pupils’ daily life experiences This series, supplemented by learning experiences outside the classroom, aims to cater for the needs and interests of pupils. It also lets pupils understand the application of science and technology in daily life in an interesting, life-oriented and diversified way, allowing them to apply their scientific knowledge to solving real-life problems. 3 Inquiry and problem-solving skills Inquiry is the process of seeking out problems and solutions. Through scientific questions and inquiry activities in the textbook, supplemented by the Scientific Inquiry Activity Booklet , this series encourages pupils to apply different scientific methods to finding solutions to problems through hands-on and minds-on activities, and cultivates evidence-based scientific thinking. 4 Values education This series enables pupils to realise that science and technology can improve people’s quality of life, and people mastering science can bring about positive changes to society, and contribute to our nation and Hong Kong. In the process of science inquiry, pupils can learn from the perseverance of scientists and experts in truth-seeking, innovation and continuous experimentation. Moreover, a learning partner named ‘Little Mentor’ is included in some units to help pupils cultivate positive values and attitudes. The ‘Back to the Past’ section allows pupils to learn about the past and present development and application of science and technology in the nation, thus enhancing their sense of national identity and national confidence. 5 Cross-curricular learning This series emphasises the collaboration between Primary Science and Primary Humanities. It features ‘Humanities Link-up’ to connect the content of the two subjects. Moreover, it includes diversified STEAM activities to let pupils apply the knowledge and skills acquired in Mathematics and Computer Studies to solving real-life problems by designing and making different models or products. Each book also features thematic reading materials so that pupils can apply the reading skills they learned from language classes in reading passages related to scientific knowledge, celebrities, and information about Hong Kong, the nation and the world. This helps broaden their horizons. 6 Self-directed learning Lead-in questions on the unit cover of every unit ignite pupils’ curiosity and interest in exploring science. Sections such as ‘Life Link’ and ‘More to Explore’ encourage pupils to explore the topic and learn beyond the classroom to achieve life-wide learning. Each unit also features a ‘Self-assessment’ section for pupils to evaluate their learning performance and reflect on more topics to explore, so as to develop their self-directed learning capabilities. Additionally, the subject website provides a wealth of learning and teaching resources to enrich pupils’ learning. (*The resources have not been reviewed by the Education Bureau.)
4 B
I will uphold my spirit of truth-seeking in science.
I will carry out scientific explorations in a fair and objective way.
Jenny
Fred
I will tell you scientific knowledge. Dr Science
Smart Thinker
When you see me, answer my questions. Check your answers on the last page of the book!
Little Mentor I will help you develop positive values and attitudes.
I will remind you of safety. Captain Safety
Name:
Class:
There is an interesting picture and some thought-provoking questions to get you into each scientific theme. You can find answers to the questions from the hints in the picture or from your daily life. Unit Cover 1
The investigative question and learning activity are organised according to the learning points of the unit. You have to learn by using your hands and your mind! 2 Investigative Question
You can use it with your textbook. It guides you to do different scientific inquiry activities, and record and analyse the inquiry results. Scientific Inquiry Activity Booklet
It allows you to record the knowledge you discovered from the activities. Quick Check
It helps you review the section. Note 3
Overview 4
This mind map helps you review what you have learned in each chapter.
It helps you think about what you know, what you can do and what you want to learn more about. Self-assessment 5
Life Link
More to Explore It gives you suggestions for visits, community learning activities, online learning and projects.
Back to the Past By linking the present to the past, you can know more about the nation’s science and technology. It provides a link to Primary Humanities so that Primary Science and Primary Humanities work better together. n i Link-up You can link what you have learned with your daily life through questions or small activities.
Reading to Learn
It reminds you to read the passages on different themes in the appendices.
Learn More
It lets you know
more about the topic.
To enhance the quality of our series, ensure the accuracy of the information, and keep the content up-to-date, EPH has invited the following professionals and organisations to review our textbooks. Should you have any queries, the consultants and EPH will be pleased to provide our opinions. Consultants and Partner Organisations
Prof Chan Lik Yuen Clinical Professor (Honorary), Faculty of Medicine, CUHK Ir Lo Kok Keung Registered Professional Engineer, Hong Kong Mr Yip Chee Kuen Former Chief Curator, Hong Kong Science Museum and Macao Science Center; Former Advisor, H 2 OPE Centre, Water Supplies Department
Dr Cheung Chok Fong Experienced Information Literacy Education Scholar
Dr Yick Ho Kuen Experienced Science Educator
Orion Astropreneur Space Academy (Hong Kong) Limited
The Hong Kong Institution of Engineers 香港工程師學會
4B Contents
Unit 5 The Road to Science Inquiry
9 Scientific Process and Advancement / 4 10 Fair Testing / 9
11 Energy / 16 12 Closed Circuits / 26 Unit 6 Energy and Electricity
13 Metals and Non-metals / 32 14 Changes of Matter / 41 Unit 7 Properties and Changes of Matter
Unit 8 Science in Daily Life
15 Properties of Light / 50 16 Friction / 56
Unit 9 Aerospace and Technology
17 Space Technology and Daily Life / 66
Appendices: Reading to Learn Glossary
Visit the subject website to view the resources: https://ephsci.ephhk.com
1. How is scientific knowledge established? 2. Does scientific knowledge remain unchanged forever? 3. What is the spirit of science? The Road to Science Inquiry
Unit 5
2
3
9 Scientific Process and Advancement Unit 5 The Road to Science Inquiry
1 How can we gain scientific knowledge through science inquiry?
1. Start with observation and asking questions
1
2
Look! The lemon tea does not overflow after the ice has melted.
This glass of lemon tea is nearly full. Ice is floating on the top. When the ice melts, will the lemon tea overflow?
Observation and asking questions
10 minutes later
4. Analyse and reflect on the result
When water freezes, the level of ice surface rises. When the ice melts, the water level drops to its original level. This proves your hypothesis.
6
Analysis and reflection
There are ways to improve this experiment. For example, it is not accurate enough to mark the water level with a rubber band. Also, …
Is our test result accurate?
If there is not enough evidence to support the original hypothesis, what should we do?
4
A ‘hypothesis’ is based on scientific theories or life experience. It is a temporary explanation to a question. It may not be correct, so it needs to be verified by scientific methods. Proposing and verifying a hypothesis need imagination and creativity.
It seems that the water surface is like a layer of elastic rubber covering the water. That’s why the water does not overflow.
2. Propose a hypothesis
3
4
Does the volume of ice decrease when it melts?
Let’s verify Fred’s hypothesis.
Hypothesis: Ice contracts when it melts, preventing water from overflowing. That is to say, water expands when it freezes.
Hypothesis
3. Test the hypothesis
Activity Booklet 16
5
Test
(1) Prepare a glass of water (about 70% full). Mark the water level with a red rubber band.
(2) Put the glass into a freezer until the water freezes.
(4) Leave the glass at room temperature. Observe the
(3) Take the glass out of the freezer. Mark the level of
change in the water level after the ice melts.
the ice surface with a green rubber band.
5
2 Does scientific knowledge change over time? Read how people explored the shape of the Earth and answer Jenny’s questions.
Long, long time ago
About 2600 years ago
Later, people observed one thing: When they were standing on land and watching a ship sailing in their direction, they could see its pole first before seeing its body. If the land was flat, this phenomenon could not be explained. Therefore, the ‘Round Earth Theory’ appeared.
People believed in the ‘Flat EarthTheory’ and thought that the land was flat.
Reading to Learn Science for You Do you want to know more examples of scientific knowledge being changed when new evidence appeared? Let’s read ‘From the Earth- centred Theory to the Sun-centred Theory’ together! Appendix 1
Why did people later overturn the previous belief of ‘Land was flat’?
6
Now
About 2200 years ago
Images taken by artificial satellites from space have proved that the Earth is round.
Greek mathematician and scientist Eratosthenes discovered that the lengths of the shadows in Alexandria and Aswan were different. These two cities were in the north and south of Egypt respectively. This disproved the ‘Flat Earth Theory’.
Imagine the land is flat. When the Sun shines on the ground directly, the length of shadows in different places should be the same. However, this is not the fact …
The Earth is really round!
imagine the land is round
imagine the land is flat
Will an accepted scientific theory or hypothesis be overturned? If yes, how will it be overturned?
Did the ‘Round Earth Theory’ gain any support from the shadow tests?
7
3 What scientific spirits and attitudes should we learn from scientists? Do you agree that studying science needs these qualities and attitudes? Put a 3 in the if you agree.
2
3
1
strict testing and reasoning
respect evidence and facts
5
4
be observant
6
always have doubts
not bound by authorities or old beliefs
be imaginative and creative
Observation and asking questions
temporary explanation
Hypothesis
Scientific process and advancement
e.g. the ‘Flat Earth Theory’ was replaced by the ‘Round Earth Theory’
Analysis and reflection
Scientific spirits and attitudes
Test
Establish new knowledge
Collect evidence
8
10 Fair Testing Unit 5 The Road to Science Inquiry
1 What is fair testing? 1. Fair testing is one of the methods used in science inquiry. Learn about what fair testing is through the inquiry process below.
1
Observe this seedling. What questions will you ask?
The light outside is stronger than that in the room. Is it better for the growth of the seedling?
Why is the seedling growing towards the window?
Why is the seedling not growing upwards?
Tim
Jenny
Fred
Observation and asking questions
Hypothesis
2
How can we test if light intensity affects the growth of the seedling?
Jenny
Test
Put a seedling in sunlight and another in a dark place, then see which one grows better.
Put a seedling in sunlight, then see how well it grows.
Tim
Put a seedling in sunlight. Put the second seedling in a place without direct sunlight. Put the third seedling in a dark place. Then, compare the growth of the three seedlings.
Fred
2. Which pupil’s test do you think is the fairest and the best answer to the teacher’s question?
9
2 2 How do we do a fair test? 1. After discussion, the pupils decided to use the method below to test if light intensity affects plant growth. Experiment design translucent box
1
There are small holes at the bottom of the box to let air in.
Plant A
Plant B
2. Based on the method chosen by the pupils, answer the three questions below. Put a 3 in the correct . (There can be more than one answer.)
Three questions to be considered for fair testing
How does light intensity affect plant growth?
(1) What factor should be tested?
How does the amount of water affect plant growth?
the sizes of the leaves
(2) What variable should be measured?
the heights of the stems
supply of air
stage of growth of the seedlings
(3) What other factors
should be controlled?
water in the soil
time for sunlight exposure
10
Let me compare the growth of the three plants by measuring the sizes of their leaves.
A week later
4
3
opaque box
Reading to Learn
Science for You How did early scientists use more objective methods to do tests? Read ‘The Pioneer of Medical Testing — James Lind’ to find out! Appendix 2
There are small holes at the bottom of the box to let air in.
Plant C
Reflection 3. Do you think this test is fair? Is there room for improvement? Discuss your ideas with your classmates.
The Road to Science
Which scientific questions cannot be answered through fair tests?
Fair testing allows us to find out accurately how a factor affects another variable .
11
3 How can we apply fair tests in our daily lives? 1. How does an apple change after it is cut open for a while? 2. How can we slow down or prevent this change in the apple? Do a fair test to find out an effective method.
Activity Booklet 17
Hints
How can we slow down or prevent this change in apples? (Propose a hypothesis.)
Design a fair test to verify if the hypothesis is correct. (Design an experiment.)
How can we ensure that the test can verify our hypothesis fairly? (Control factors.)
Fair testing
Three elements
Test only one factor
Control other factors
Measure the affected variables find out the effect
keep constant
12
Well done
Good
Try harder
assessment
Before you do the assessment, revise the key concepts of this unit first. Can you do these things? Put a 3 in the .
Knowledge and Understanding
State the process of establishing scientific knowledge. Explain that scientific knowledge changes when new evidence appears with the example of ‘Round Earth Theory’ replacing ‘Flat Earth Theory’. Explain what fair testing is and state three elements of it. Explain with examples the uses of fair tests.
9
10
Skills and Processes
Propose hypotheses for scientific questions based on scientific theories or life experience. Apply fair tests to explore the scientific questions I find in daily life.
9
10
Values and Attitudes
Develop scientific spirits and attitudes. Apply fair testing in scientific tests.
9
10
1. Which topic in this unit interests you the most? What specific question do you want to explore further?
2. Which methods are you going to use when you explore the question? Put a 3 in the . observe do surveys do experiments search for information
do projects
write scientific journals
read books
others:
13
Unit 6 Energy and Electricity
3. Are Fred and Jenny wasting energy? Why or why not? 1. Which of the things in the pictures need energy to run? What kinds of energy do they use? 2. What electrical appliances usually have switches?
14
15
Energy and Electricity Unit 6
11 Energy
1. What are some common sources of energy? Look at this flow chart and talk about them. 1 Where does energy come from?
1
Coal, oil and natural gas are formed underground. We need to get them from underground or under the sea.
coal
coal
oil
3
natural gas
electricity
oil products
2. According to the flow chart, what are the uses of coal, oil and natural gas? power plant
1
2
3
coal
oil
natural gas
16
Life Link Which two companies supply electricity in Hong Kong? Which sources of energy do they mainly use to produce electricity?
2
Castle Peak Power Station
Learn More Town gas production in Hong Kong ․ Since the 1960s, oil products have replaced coal to produce town gas. ․ Since 1999, landfill gas has been used. ․ Since 2006, natural gas, along with oil products, have been used. Now, around half of the composition of the town gas produced in Hong Kong is hydrogen. However, we still call this gas fuel ‘town gas’.
natural gas oil
oil
diesel
4
petrol
oil refinery
LPG
Source: The Hong Kong and China Gas Company Limited
Quick Check ,
and are common sources of energy. They are limited and are renewable / non-renewable .
town gas production plants in Hong Kong
17
Renewable energy will not be used up. It is a resource that can be regenerated endlessly in nature.
3. How can we use renewable energy to produce electricity? Look at the pictures. Write the answers on the or circle the correct answers.
水力能 Hydropower
1
How electricity is produced: Hydropower plants use the force of that flows down from a high place to produce electricity.
太陽能 Solar power
2
How electricity is produced: Use the energy produced by the __________ to produce electricity.
風能 Wind power
3
How electricity is produced: Use _____________ to drive the electricity generator. When the generator is larger / smaller and the wind speed is higher / lower , more electricity is produced.
18
Learn More Sources of energy
4. Read this article to learn about measures taken by Hong Kong to promote renewable energy. Answer the questions.
Coal, oil, natural gas, wind power, hydropower and
Promoting Renewable Energy Development
solar power all come from nature directly, so they are called ‘primary energy’. However, it is not easy to transport and use them. Therefore, power plants convert them to electricity, which is convenient to use. Electricity is called ‘secondary energy’. Which kind of renewable energy is not developed in Hong Kong? Why?
Since 2018, the two power companies in Hong Kong have introduced Feed-in Tariff (FiT). Its goal is to encourage their clients to join the companies in using renewable energy to produce electricity. After the clients have installed the solar-energy or wind-energy systems, they can sell the energy they produce to the power companies at a rate higher than the normal electricity tariff rate. This helps the clients get their investment cost back and encourages them to invest in renewable energy.
Source: ‘HK RE Net’ website
(1) How do the power companies encourage their clients to support the development of renewable energy? (2) Besides the measure mentioned in the article, what other facilities in Hong Kong use renewable energy to produce electricity? 5. Make a toy car that uses wind power to run. Find out how the strength of the wind and the size of the sail affect the speed of the toy car. Activity Booklet 18
More to Explore
Do a project on the topic ‘renewable energy’. Search for information about a kind of renewable energy. 1. What is the source of this kind of energy? 2. What are some examples of using this kind of energy in Hong Kong and other places around the world?
Renewable energy will not run out. e
3. What are the
limitations of its development?
19
2 Do we need to use energy in our daily lives? 1. Look at what Jenny does in a day. In which activities does she use energy? What kinds of energy does she use in each activity?
3
2
1
Come and take a look at my everyday life!
11
10
9
2. Record your activities for a day. Find out in which activities you use energy and tell your classmates about them. Activity Booklet 19
20
Back to the Past People in the past had no electricity. What energy did they use in daily life?
4
5
1
2
School
6
3
Learn More Energy that sustains life Food and the Sun are both sources of energy. Energy in food can keep us alive. Energy from the Sun brings warmth and lights up the world.
7
8
21
3. Besides daily activities, different industries also need energy. Write the correct letters in the .
A. manufacturing industry B. transport industry C. agriculture
2
1
3
4
6
Different industries
5
7
4. Imagine that there is no energy. How will these industries be affected?
Our daily activities and different industries need energy. e
22
1. Discuss these questions in groups. (1) Why do we need to use less non-renewable energy? 3 Why should we save energy?
Reading to Learn
Global Vision What are green buildings? Name some green buildings in Hong Kong and other places. Read ‘Green Buildings’ to know more.
Carbon dioxide is usually produced when we use non-renewable energy ...
Non-renewable energy is limited. It will ... one day.
Appendix 3
More to Explore
Visit CLP Power’s Low Carbon Energy Education Centre to learn about the important role of low carbon energy in dealing with climate change.
(2) Many people say that we should replace non-renewable energy with renewable energy. What benefits will this suggestion bring?
23
2. Based on the information, answer the questions.
Global Use of Energy in 2022
File A
10 15 20 25 30 35
5 0
oil
coal
natural gas
nuclear power
hydropower wind power
solar power
others
non-renewable energy
renewable energy
Sources of energy
Source: Our World in Data website
Limitations of Developing Renewable Energy
File B
1
2
3
unstable weather
dry climate
limited supply of land
(1) In 2022, did the world mainly use non-renewable energy or renewable energy? (2) Why has renewable energy not become common and the main source of energy in the world?
24
3. Do these activities and apply your knowledge.
(1) Look at the pictures of what Jenny does on pages 20–21 again. Do Jenny and her family do anything to save energy? Can you give them some advice? (2) How can we save energy at home and at school? Activity Booklet 20
We need to cherish energy and use it wisely. e
wind power
solar power
hydropower
coal
oil natural gas
Non-renewable energy
Renewable energy
limitations in their development
will be used up
will not be used up
Sources
Energy
turning off unnecessary appliances
lighting
making products
Use of energy
Save energy
using fewer appliances
using more natural light
using electrical equipment
transport cooking
25
Energy and Electricity Unit 6
12 Closed Circuits 1 How can we light up a bulb? 1. Megan turned on the switch of her electric lantern, but the lantern did not light up. Guess the reason.
2. These circuit components make the lantern light up. Write their names on the and look at their uses.
: connects the light bulb to the dry batteries
: supplies power, and has positive and negative poles
: turns electrical energy into light energy
3. How should we connect a bulb and a dry battery to light up the bulb? Assemble these circuit components.
Activity Booklet 21
light bulb with a holder
wires with crocodile clips
dry battery
battery holder
To light up a bulb, we need to connect it to and to form a closed circuit. Quick Check
26
2 What does a switch do in a circuit? 1. How can you improve the circuit you connected to make it more convenient to use? 2. What electrical appliances at your home have switches? What are these switches for?
More to Explore Use a buzzer to replace the light bulb with a holder in the closed circuit. See whether the buzzer can make sounds or not.
1
2
3
Activity Booklet 22 3. Add this switch to a circuit. Then, open and close the switch to see how it controls the bulb to light up or not.
Listen to your teacherÕs instructions when you
assemble circuit components. When there is overheating in circuits, disconnect them at once and tell your teacher.
4. Make a switch and add it to the circuit you connected in Activity 21 . Activity Booklet 23
Quick Check Electrical appliances may use switches to control the operation of circuits. When the switch is open, it connects / disconnects the circuit. When the switch is closed, it connects / disconnects the circuit.
27
3 Why does the bulb not light up? 1. When you were doing the activities in questions 1 and 2, were there times when
the bulb still did not light up in a closed circuit? 2. What may be the causes of the above situation?
Is the light bulb burned out?
Is the battery dead?
Are the wires loose?
Closed circuits
Main components
Components that turn electrical energy into other forms of energy
Power source
Connection
positive pole
negative pole
light bulb
switch
buzzer
wire
dry battery
connects and disconnects a circuit
28
Well done
Good
Try harder
Before you do the assessment, revise the key concepts of this unit first. Can you do these things? Put a 3 in the . assessment
Knowledge and Understanding
Identify sources of energy. List daily activities that need energy and state the kinds of energy used. State the weaknesses of non-renewable energy, as well as the strengths of renewable energy and limitations of developing it.
11
Explain what a closed circuit is. State the uses of the three main parts of a circuit. Explain the uses of switches in electrical appliances.
12
Skills and Processes
Make a wind-powered toy car to explore how the strength of the wind and the size of the sail affect the speed of the toy car. Take actions to save energy at home and at school. Make a closed circuit by assembling the circuit components. Add a switch to the circuit I made. Find out why the circuit did not work.
11
12
Values and Attitudes
Cherish and save energy.
11
Pay attention to safety and note if there are any abnormal situations when I make a circuit.
12
1. Which topic in this unit interests you the most? What specific question do you want to explore further?
2. Which methods are you going to use when you explore the question? Put a 3 in the . observe do surveys do experiments search for information
do projects
write scientific journals
read books
others:
29
1. What materials are kitchen utensils made of? Which of them are metals? Which of them are non-metals? 2. Matter in the kitchen often changes. What changes produce new matter? Properties and Changes of Matter
Unit 7
30
31
13 Metals and Non-metals Unit 7 Properties and Changes of Matter 1 How can we distinguish between metals and non-metals? 1. In our daily lives, we often see objects made of metal. Which of the following are the common properties of most metals? Put a 3 in the correct .
shiny and can reflect light
1
3 white
2 elastic
4 hard
5 opaque
2. Based on the properties you chose, identify which of these objects are made of metal. If it is made of metal, put a 3 in the . If not, put a ✗ .
2
1
3
5
4
9
6
8
7
3. Apart from the properties that we can see and feel, what other common properties do metals usually have?
32
1. Fred finds a hair dryer at home. A part of the cable is broken and he sees a golden-brown wire inside the blue outer jacket. What are the blue jacket and golden-brown wire made of? Are the materials metals or non-metals? 2 What is the difference between the electrical conductivity of metals and non-metals?
I just realised that a cable is made of different materials. Why does it have such a design?
inner wires
outer jacket
If you find the cable broken, stop using the appliance at once to prevent electric shocks. Tell an adult about it.
Activity Booklet 24 2. What is the relationship between the design of the cable and the electrical conductivity of materials? Work in groups to do a test with the objects on page 32 (part 2). Analyse the electrical conductivity of metals and non-metals to find the answer.
dry battery
Experiments involving electricity can be dangerous. Do them only when an adult is present!
battery holder
light bulb with a holder
wires with crocodile clips
Metals can / cannot conduct electricity. They are electrical conductors. Most non-metals can / cannot conduct electricity. They are insulators. Quick Check
33
3 How can we apply electrical conductivity to the design of products? Look at the picture and answer the questions. (1) An electric kettle gets electricity from a socket through a plug and a cable. Observe the different parts of the electric kettle. If the part is made of metal, put a in the . If the part is made of non-metal, put a . (2) Why do we use metals and non-metals to make different parts of the products? ○ △
Learn More
Life Link Why do we often find a strip of plastic or paper inside the battery holder of a new electronic product? higher output, wires are normally made of copper. followed by copper. As silver is expensive and copper is cheaper with Electrical Conductivity and Price of Metals The electrical conductivity of metals is much higher than that of non-metals. However, different metals have different electrical conductivity. Silver is a great electrical conductor,
electrical connectors 2
pin 3
base 1
case 4
plug
socket
electric kettle
outer jacket 5
cable
inner wires 6
34
1. Look at the picture below. Why do Fred’s and Jenny’s spoons feel different? 4 What is the difference between the thermal conductivity of metals and non-metals?
The spoon is so hot!
Mine doesn’t feel hot.
Activity Booklet 25 2. Do this experiment to compare the thermal conductivity of metals and non-metals.
plastic rod
wooden rod
copper rod
butter
a glass with hot water
Quick Check Copper (metal) conducts heat more quickly / slowly . It is a good / poor thermal conductor. Wood and plastic (non-metals) conduct heat more quickly / slowly . They are good / poor thermal conductors.
35
1. What are different parts of these cooking utensils made of? Why are these materials chosen? Circle the correct answers. 5 How can we apply thermal conductivity to the design of products?
The handles of the spatula and the pan are made of metal / non-metal , which is a good / poor thermal conductor. They insulate heat to prevent burn injuries.
The frying pan is made of metal / non-metal , which is a good / poor thermal conductor. It is suitable for cooking.
36
2. Are the materials used to make these kitchen utensils good or poor thermal conductors? Write the correct numbers on the and circle the reasons for using these materials. plastic cup sleeve 1
wooden spatula
2
cloth oven glove 3
metal baking mould
4
wooden coaster 5
metal pot 6
Good thermal conductors: they conduct / insulate heat. Poor thermal conductors: they conduct / insulate heat.
;
;
37
6 How can we use suitable materials to make an insulated bag?
1. What problem does Jenny have? What is Fred’s suggestion?
Why don’t you apply your knowledge of thermal conductivity to design an insulated bag?
In winter, warm water gets cold quickly but it’s inconvenient to carry a heavy vacuum bottle around.
How can you introduce your insulated bag to your classmates? What is special about your insulated bag? Presentation and r eflection
7
Improvement 6
Do the test results match your prediction? How can you improve your design?
Testing and analysis 5
How can you test the insulation performance of the bag? How can you record the test results? How can you prove that the water is kept warm because of the insulated bag, but not other factors?
We may face different problems and constraints when we design and make a product. We need to be patient and creative.
38
2. Follow the engineering design process and make an insulated bag that meets your needs. Test its insulation performance.
Activity Booklet 26
I always carry my water bottle when I go out.
Defining the p r oblem
1
Apart from keeping water warm, what other requirements should the insulated bag meet?
Collecting information 2
What materials insulate heat better? How can you reduce the weight of the bag? How can you make the bag beautiful and useful?
Engineering design process
Drawing a design 3
What parts does your design have? What materials are the parts made of? What are the uses of the materials?
Making the product 4
How can you glue different materials together? What safety precautions should you take when you make the product?
Engineering design process includes defining the problem, collecting information, and designing, making and testing the product. It also involves improving and reflecting on each step. This is a cycle process. e
39
3. Comment on other classmates’ work and choose the best design in different areas, such as the bag that has the best insulation performance, the most creative bag and the most beautiful bag.
My bag is made up of different parts, such as … The innermost layer is made of … It can … To make the bag more beautiful, I …
Properties of matter
metal pot
Good thermal conductors
Poor thermal conductors
Non–metals
Metals
most of them
Electrical conductors
Insulators
wire
Engineering design process
P resentation and reflection D efining the problem
C ollecting information
D rawing a design
M aking the product
I mprovement
T esting and analysis
40
14 Changes of Matter Unit 7 Properties and Changes of Matter
1 Does a change in the state of matter produce new matter?
1. We often see changes in matter around us. Have you noticed if the matter has just changed its state or has produced new matter? 2. Look at these pictures carefully. What process of change does water go through? Does the process produce new matter?
1
boiling water
2
3
water droplets formed on a soft drink can
making ice cubes
Quick Check When water is changing its state, it produces / does not produce new matter.
41
1. Observe the changes in these objects. Are there any changes in their colours and textures? Do they produce new matter? (1) Stretch and squeeze these objects. 2 Does the change of an object’s shape produce new matter?
When we squeeze an orange to make orange juice, does it produce new matter?
1
2
Learn More
The Melting and Recycling of Metals We can recycle gold jewellery, aluminium cans, waste iron and other waste metals by melting them. The state of metals will change during the melting process, but they will not produce new matter.
squeezing some modelling clay
stretching a rubber band
(2) Observe the changes in these objects after they broke.
1
2
shredded wood
shattered glass
2. In everyday life, what are other examples of visible changes that do not produce new matter?
Changes that do not produce new matter are physical changes. e
42
1. Observe the changes in paper burning. After burning the paper, are there any changes in its colour and texture? Does the process produce new matter? 3 What changes produce new matter in everyday life?
Burning objects may cause burns and even fires. Do not burn things on your own!
1
2
after burning
After paper burns, it becomes ash, water vapour and some gases.
Quick Check Paper burning produces / does not produce new matter.
2. Observe the changes of the iron nail. Does rusting produce new matter?
1
2
rusty iron nail
normal iron nail
3. Compare the characteristics of the iron nails in pictures 1 and 2 in part 2. Answer these questions. (1) Observe: Are there any differences in their colours? Which one is shiny? Which one is smoother? Which one is rougher? Activity Booklet 27
How else can you compare the normal iron nail with the rusty iron nail?
(2)
Test with a magnet: Which one is attracted to a magnet more easily?
When iron rusts, it produces / does not produce new matter. There is a small / big difference between rusty iron and normal iron. Quick Check
43
4. Observe the change in the strawberries below and answer these questions.
Wear a mask when you observe mouldy food. Wear gloves or use tools instead of your hands when you touch mouldy food.
1
2
after some time
fresh strawberries
mouldy strawberries
(1) After leaving the strawberries out for some time, what do they look like? (2) Touch the mouldy strawberries. How has their texture changed? (3) Do the mouldy strawberries produce new matter?
5. Discuss in groups. Give more examples of decaying matter.
2
1
Decayed food is bad for health. Do not eat it!
spoiled milk with a sour taste
decayed leaf
Changes that produce new matter are chemical changes. e
44
4 How can we tell the differences between physical and chemical changes?
1. What are the differences between physical and chemical changes?
Physical changes do not produce new matter while chemical changes do. How can we tell if new matter is produced?
Let’s take a look at the food we often eat!
2. Observe the two eggs in the pictures. Has the colour of the boiled egg changed? Is the change of the egg during cooking a physical change or a chemical change? Activity Booklet 28
1
2
cook in boiling water
raw egg
boiled egg
3. Is it possible for matter to go through both physical and chemical changes during the changing process? Observe the burning candle carefully and answer these questions.
(1) What happens at the bottom of the candle flame? (2) Is new matter produced when burning? Where can we observe it?
burning candle
45
5 How do physical and chemical changes affect humans and nature? Matter on the Earth goes through physical and chemical changes all the time. Discuss whether the examples in the pictures are physical or chemical changes, and the effects they have on humans and nature.
Reading to Learn Science for You
Read ‘Matter Decay’ to learn about chemical changes in nature. Appendix 4
1
2
burning coal and oil
raining
3
food waste compost
Changes of matter
produce new matter
do not produce new matter
Physical changes
Chemical changes
Change of state
Change of shape
Burning
Rusting
Decaying Cooking
freezing dissolving
squeezing
46
Well done
Good
Try harder
assessment
Before you do the assessment, revise the key concepts of this unit first. Can you do these things? Put a 3 in the .
Knowledge and Understanding
Distinguish between objects made of metals and non-metals. Compare the electrical conductivity of metals and non-metals, and relate their properties to their uses. Compare the thermal conductivity of metals and non-metals, and relate their properties to their uses. Determine whether a material can be used for conducting heat or insulating heat based on its properties. Identify some physical changes and list some common examples. Identify some chemical changes and list some common examples. State the effects of physical and chemical changes on humans and nature.
13
14
Skills and Processes
Make an insulated bag that meets my needs according to the engineering design process.
13
Values and Attitudes
Design a product with my creativity and imagination, and keep improving the design. Solve problems I face during the product making process with patience and a positive attitude.
13
1. Which topic in this unit interests you the most? What specific question do you want to explore further?
2. Which methods are you going to use when you explore the question? Put a 3 in the . observe do surveys do experiments search for information
do projects
write scientific journals
read books
others:
47 47
48
1. Imagine light disappears suddenly. What will happen to Fred and Jenny? 2. Where can you see the reflection of light in this picture? 3. Why are there treads on shoe soles and the wheels of bicycles? Science in Daily Life
Unit 8
49
15 Properties of Light Unit 8 Science in Daily Life
1 How does light let us see things? 1. Look at this picture. Where does the light Fred sees come from?
2. Walls do not give off light, but why can Jenny still see them?
3. What gives off light in our daily lives? Give some examples.
Quick Check
We can see things only when there is
. Light can come from
a
, or from the
of an object.
50
2 How does light travel?
1. Do you remember how shadows are made? This paper puppet blocks the path of light. What appears on the wall?
source of light
Do not shine the table lamp in your own or other peopleÕs eyes.
table lamp
2. Replace the paper
puppet with a mirror. In which direction does the blocked light travel? Do this experiment. Draw the path of the light on the picture using .
source of light
table lamp
Quick Check When light shines on the mirror, the mirror reflects / does not reflect it and it changes the direction it travels.
51
3 Which everyday phenomena are related to the reflection of light? 1. Why can we see ourselves in mirrors? 2. Compare the images formed in a plane mirror and on aluminium foil. Explain the difference based on what you know.
1
2
image formed in a mirror
image formed on aluminium foil
3. Do this experiment to explore the reason for the different images formed in a plane mirror and on aluminium foil.
Activity Booklet 29
1
2
light
light
mirror
aluminium foil
Quick Check When light shines on a smooth surface, the surface reflects it in a specific direction / many directions and a clear / blurred image is formed. When light shines on a rough surface, the surface reflects it in a specific direction / many directions and a clear / blurred image is formed.
52
4. Answer the questions using your knowledge of the reflection of light. (1) What causes the reflection of the tram?
1
2
source of light
water on the ground
Cause of reflection
(2) Why are the reflections of this dog different?
1
2
reflection on a calm water surface
reflection on a rippled water surface
53
4 What other phenomena of light reflection are there in daily life? 1. Turn off the lights, projector and other sources of light in the classroom. Can we see things in the classroom? If yes, where does the light come from? 2. In the evening, there is a power failure at Jenny’s home. Can she see the things at home? Why or why not?
The torch is here.
3. A long time ago, when there were no streetlights, people had to rely on the Moon to guide their way at night. The Moon does not give off light. Why does it look bright? Explain the reason using your knowledge of the reflection of light.
Moon
sunlight
Earth
54
4. Look at the picture. What reflectors are there on roads and in cars to ensure the safety of drivers and pedestrians?
What is light pollution? How is it related to the reflection of light?
Sources of light
Reflection of light
Reflection from a smooth surface
Reflection from a rough surface
produces
produces
clear image
blurred image
55
16 Friction Unit 8 Science in Daily Life
1 What is friction? 1. Force can make objects move. Push an eraser on the table with force. What kind of force is it? 2. Why does the eraser stop moving eventually even if you do not block it?
1
The eraser starts to move.
pushing force
2
The eraser slows down.
direction of friction
direction of motion
3
The eraser stops.
Quick Check When two objects, such as an eraser and a table, are in contact, resistance acts on their motion. It will slow down and even stop the motion. The resistance is called .
56
3. Look at the pictures on page 56. Describe the relationship between the direction of motion and the direction of friction. 4. Look at these pictures. In the , draw to show the direction of the cardboard box’s motion and to show the direction of friction.
1
push to the left
2
pull to the right
Friction acts in the same / opposite direction to the motion. Therefore, we feel resistance when we move objects. Quick Check
57
2 What factors affect the size of friction? 1. Look at the pictures on page 57. Imagine Fred is pulling a very heavy object. Will the friction acting on the object increase so that it is harder for him to pull the object? 2. Use a spring balance to pull a wooden block with different weights. Find out how the size of friction is different.
Activity Booklet 30
lift ring
The larger the pulling force acting on the spring balance, the longer the spring stretches and the greater the reading. When we use a spring balance, we should: (1) lift the spring balance vertically
spring
pointer
scale plate
and check whether the pointer is pointing at ‘0’. If not, move the scale plate and adjust the pointer until it points at ‘0’.
hook
‘N’ is the unit of force.
(2) place the pointer at eye level when we read the reading.
(3) keep the force we want to test below the maximum reading on the scale of the spring balance.
Quick Check The heavier the object, the greater / smaller the friction it creates when it moves on a surface.
58
3. Which of the following surfaces allows objects (e.g. luggage) to slide more smoothly? Why?
1
2
pavement
airport concourse
The smoother the surface on which an object moves, the greater / smaller the friction. Quick Check
4. Do an experiment. Compare the friction acting on a toy car when it moves on different surfaces. Verify if the statement in the ‘Quick Check’ above is correct. Activity Booklet 31
1
2
3
paper
fine sandpaper
coarse sandpaper
Factors that affect the size of friction are: (1) the weight of an object; (2) whether the surface of an object is smooth or rough. e
59
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