4 A
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 A
Fred
I will carry out scientific explorations in a fair and objective way.
Jenny
I will uphold my spirit of truth-seeking in science.
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
4A Contents
Unit 1 About the Earth
1 Structure of the Earth / 4 2 Movement of the Earth / 12 3 Weather and Climate / 17
Unit 2 Living Things and Environment
4 Animals, Plants and the Environment / 28 5 Balance of Nature / 39
Unit 3 Continuation of Life
6 Reproduction and Heredity of Plants / 50 7 Reproduction and Heredity of Animals / 57
Unit 4 Prevention Is Better than Cure
8 Infectious and Non−infectious Diseases / 68
Appendices: Reading to Learn Glossary
Visit the subject website to view the resources: https://ephsci.ephhk.com
About the Earth
Unit 1
1. How many layers does the Earth have? 2. Is the place where Fred stays day or night? 3. Why are the climates of the places where Fred and Jenny stay different?
2
3
1 Structure of the Earth Unit 1 About the Earth
1 What is the structure of the Earth?
1. The Earth has three layers. What are the characteristics of each layer? Write the correct letters on the .
A. It contains hot flowing magma. B. It is the centre of the Earth. It is mainly made up of metals. The temperature is extremely high. C. It is the outermost layer of the Earth. It is mainly made up of rocks. It is divided into many plates.
crust:
mantle:
core:
2. In which layer of the Earth do we live? 3. Is a hard boiled egg like the Earth? Can we use it to simulate the Earth’s structure? Work in groups and discuss how it can or cannot simulate the Earth’s structure.
4. Work in groups. Create a model of the Earth using different materials, such as modelling clay and waste paper. Introduce your model to other classmates and tell them how it simulates different parts of the Earth.
4
1. What are the characteristics of the Earth’s crust? Is it a complete piece? 2 How is the Earth’s crust changing? What natural phenomena may it cause?
Plates of the Earth
N
Arctic Ocean
Asia
Europe
North America
Atlantic Ocean
Hong Kong
Pacific Ocean
Africa
Pacific Ocean
South America
Indian Ocean
Oceania
Plate boundaries
Antarctica
2. Plates move slowly when magma in the mantle flows. What natural phenomena may plate movement and collision cause? Look at the pictures and explain. The plate boundaries were drawn in reference to the display board of the Stephen Hui Geological Museum at the University of Hong Kong.
1
2
The ground shakes violently.
Magma gushes out of a volcano.
我發現 The crust is divided into and collision may cause Quick Check
of different sizes. Plate movement
or
.
5
3 What is the Earth’s crust made up of? Look at the story of rocks and answer the questions.
1
2
3
Hello! I am a rock, the main member of the Earth’s crust.
We were formed when the magma ejected by a volcano cooled and hardened into rocks.
The Earth was formed about 4.5 billion years ago.
We rocks have changed into different types because of volcanic eruptions, changes in the Earth’s crust and other factors, such as high temperatures and sedimentation.
4
5
Some rocks broke into soil after being exposed to wind and rain for many years.
6
Parts of the crust are covered by water. They form rivers, lakes and oceans.
Therefore, people can find rocks and soil on the crust.
(1) What is the Earth’s crust mainly made up of? (2) How is soil formed?
6
4 What types of rocks are there? What are the differences in their formation?
1. What are the different types of rocks shown below?
Types of rocks
A. igneous rocks
B. sedimentary rocks
C. metamorphic rocks
1
2
3
4
5
6
granite
basalt
sandstone
shale
marble
gneiss
2. How are different types of rocks formed? Look at the picture below. Refer to question 1, write the correct letters in the .
rock formed by the sedimentation of rock pieces and soil transported down by water
rock formed when magma cools and hardens
1
2
3
rock formed when different types of rocks change their structures under high pressure and high temperature
Based on the differences in their formation, rocks can be classified into igneous, sedimentary and metamorphic rocks. e
7
Learn More
1. Use tools to compare the colours, grain sizes and hardness of different types of rocks. 5 What are the characteristics of different types of rocks? What are their uses?
Fossils Fossils are the remains of animals or plants that stayed on the riverbed or seabed, or covered by volcanic ash. They are buried within sedimentary rocks, and eventually become fossilised.
Activity Booklet 1
1
2
3
granite
sandstone
marble
我發現 Rocks have different colours. Among the three samples, has the largest grains. is the hardest. Quick Check
fossil
Back to the Past Why did people in the past use rocks to make these tools? More to Explore Visit the Stephen Hui Geological Museum at the University of Hong Kong or Nina Park to learn more about rocks.
2. How do people use the unique features of the different types of rocks to make different things?
1
3
1
2
mortar and pestle
2
stone pot
8
6 What are the components of soil? 1. Observe moist soil collected from the school garden. Discuss your observations with your classmates.
Wash your hands after touching soil. Cover any wounds on your hands with plasters or gauze.
2. Use these methods to observe soil and learn more about its components. Let’s do it!
Activity Booklet 2
1
2
？
Observe the soil with a magnifying glass.
Measure the weight of the soil.
3
4
Sieve the soil.
Put water into the soil. Stir gently.
我發現 Quick Check The components of soil include soil particles of different sizes / animal and plant matter / water / air .
9
7 What are the characteristics of different types of soil? What plants are they suitable for? 1. Jenny and Fred both enjoy gardening. They are asking the florist to recommend the right soil for the plants they like.
Which type of soil is suitable for cacti to grow?
How about roses?
Cacti are suitable to grow in drier soil, while moister and aerated soil suit roses more. Let’s look at different types of soil together!
2. Observe and record the characteristics of these three types of soil. Then, do this experiment to test how well they drain.
Activity Booklet 3
sandy soil
loam
clay soil
3. Based on the observation and test results, which type of soil is suitable for cacti? Which type is suitable for roses? Why? Soil is divided into three types based on particle size. The drainage capacity of different types of soil is different and they are suitable for growing different plants. has the smallest particles. has the largest particles. has medium-sized particles. Quick Check
10
Let me bring this rock back home.
4. Rocks and soil are
1
2
important resources on the Earth. Why are these children not doing right?
e
Rocks and soil are precious resources. We should cherish and protect them.
Structure of the Earth
Igneous rocks
different colours, grain sizes and hardness
Sedimentary rocks
Rocks
Metamorphic rocks
Mantle
Core
Crust
centre of the Earth, extremely high temperature
hot flowing magma
outermost layer, divided into many plates
Sandy soil
different drainage capacity
Soil
Loam
Clay soil
11
2 Movement of the Earth Unit 1 About the Earth
1 Why is there day and night? 1. Day and night repeat on a regular basis. Why? Make a guess.
2. The Earth rotates on its axis, which is an imaginary line passing through the North Pole and the South Pole. Shine a torch on a globe to simulate how the Sun shines on the rotating Earth. Then, explain why there is day and night.
1
paper puppet
Hong Kong
Earth’s axis
Use some tape to fix the paper puppet at the location of Hong Kong on the globe. Shine the torch on that spot.
2
3
Without moving the torch, rotate the globe anticlockwise for a half turn.
Rotate the globe anticlockwise for another half turn.
Explanation: It is bright / dark in Hong Kong when it faces the Sun, so it is
day / night . When the globe rotates for a half turn, Hong Kong turns away from the Sun. It is bright / dark there, so it is day / night .
Quick Check
The cycle of day and night is caused by the
of the Earth.
12
More to Explore People in the past used shadows of objects to tell the time. The device for observing shadows is called a ‘sundial’. You can visit the Astropark in Sai Kung or the Yuen Chau Kok Park in Sha Tin to learn about different kinds of sundials.
3. Visit the Hong Kong Observatory website to find out the time of sunrise in Hong Kong in the past two days. How much time had passed between one sunrise and the next?
Date and time of sunrise
The first day
Time passed: about hours
On
, at
a.m.
The second day
On
, at
a.m.
Quick Check
我發現 The Earth needs
1
hours to complete a full rotation,
which is
day.
Do this activity to make a sundial and find out how its shadow changes in the sunlight at different times of the day. Activity Booklet 4 2 How do shadows change in the sunlight at different times of the day?
Astropark
2
Yuen Chau Kok Park
Why can we use sundials to tell the time?
我發現 Quick Check
At different times of the day, shadows formed in the sunlight are the same / different in terms of length and direction.
The Sun does not move around the Earth. We see sunrise and sunset because the Earth rotates.
13
3 Why are there different seasons? 1. Look at the picture on the right and write the correct answers on the . (1) Besides rotation, the Earth also moves around the . This is called revolution. (2) A complete revolution takes a , which is about 365 days.
Revolution of the Earth
Hong Kong
2. What is special about the axis of the Earth? Analyse the relationship between the angle of sunlight and the changes of seasons in the two hemispheres. Circle the correct answers and write the correct seasons on the .
When the northern hemisphere receives overhead sunlight:
1
northern hemisphere equator
Hong Kong
southern hemisphere
sunlight
Earth’s axis
Melbourne
Hong Kong
The temperature in the northern hemisphere becomes higher / lower as it receives stronger / weaker sunlight. It is in the northern hemisphere and in the southern hemisphere.
Melbourne, Australia
14
3. Is Hong Kong in the northern hemisphere or the southern hemisphere? Write the seasons in Hong Kong in the in the picture on the left.
spring
Hong Kong
autumn
When the northern hemisphere receives slanted sunlight:
2
Hong Kong
Earth’s axis
northern hemisphere
sunlight
equator
southern hemisphere
Melbourne
Hong Kong
Melbourne, Australia
A complete revolution of the Earth takes a . Since the Earth’s axis is tilted, different places receive sunlight at different angles at different times of the year. This results in the changes of . Quick Check The temperature in the northern hemisphere becomes higher / lower as it receives stronger / weaker sunlight. It is in the northern hemisphere and in the southern hemisphere.
15
What is a leap year? Why are there leap years?
day
night
Day and night
rotation
Rotation and revolution of the Earth
Changes of seasons
revolution
northern hemisphere spring
northern hemisphere summer
northern hemisphere winter
northern hemisphere autumn
16
3 Weather and Climate Unit 1 About the Earth
1 What is the difference between weather and climate?
1. Visit the Hong Kong Observatory website. How does the Hong Kong Observatory describe the weather? Fill in the information about the weather today.
Activity Booklet 5
Quick Check The Hong Kong Observatory: 1. uses temperature / relative humidity to describe the coldness and the hotness of the weather. 2. uses temperature / relative humidity to describe the dryness and the wetness of the weather. 3. uses a picture to show whether there is rainfall.
2. Work in groups and discuss if Hong Kong’s temperature today is normal. Find out the answer from this graph. Activity Booklet 5
Hong Kong
Monthly average temperature and rainfall in Hong Kong (in a 30-year period)
Temperature (°C)
Rainfall (mm)
500 450 400 350 300 250 200 150 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
40 35 30 25 20 15 10
1. Weather changes every day. However, when we observe it for a long period of time, we can see that there is a regular pattern for the changes. 2. Such a pattern is referred to as climate. It is the average weather condition over a longer period of time in the past.
5 0 –5 –10
Total rainfall Average lowest temperature Source: Hong Kong Observatory website, HKSAR Government Average highest temperature
17
2 How is the climate of Hong Kong different from other cities in the world? 1. Compare the temperature, rainfall and relative humidity in Hong Kong, Beijing, Singapore and Canberra. Find out their characteristics and circle the correct answers.
Beijing
Singapore
1
2
Monthly average temperature and rainfall in Beijing (in a 30-year period)
Monthly average temperature and rainfall in Singapore (in a 30-year period)
Temperature (°C)
Rainfall (mm)
Temperature (°C)
Rainfall (mm)
500 450 400 350 300 250 200 150 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
40 35 30 25 20 15 10
500 450 400 350 300 250 200 150 100 50 0
40 35 30 25 20 15 10
5 0 –5 –10 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
5 0 –5 –10
Total rainfall
Average highest temperature
Average lowest temperature
Total rainfall
Average highest temperature
Average lowest temperature
(1) Which place is similar to Hong Kong in terms of temperature changes over the year?
Beijing / Singapore / Canberra
(2) Which place is opposite to Hong Kong in terms of temperature changes over the year?
(3) Which place has smaller temperature changes over the year? Beijing / Singapore / Canberra
Hong Kong / Beijing / Singapore / Canberra
Do you know where these places are? Find their locations on a globe. (1) Beijing is in the northern hemisphere / southern hemisphere . (2) Canberra is in the northern hemisphere / southern hemisphere . (3) Singapore is near / far from the equator.
How are the seasons of these places related to their locations on the Earth? When it is winter in Beijing, it is winter / summer in Canberra. When it is summer in Beijing, it is winter / summer in Canberra. Singapore has / does not have four distinct seasons.
18
Comparing the relative humidity of the four cities Monthly average relative humidity in the four cities (in a 30-year period)
Canberra
3
4 Relative humidity (%)
Monthly average temperature and rainfall in Canberra (in a 30-year period)
Temperature (°C)
Rainfall (mm)
100 90 80 70 60 50 40 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
500 450 400 350 300 250 200 150 100 50 0 Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
40 35 30 25 20 15 10
5 0 –5 –10
Total rainfall
Average highest temperature
Average lowest temperature
Hong Kong
Beijing
Singapore
Canberra
Sources: Hong Kong Observatory website, HKSAR Government; websites of the meteorological authorities of relevant places
Hong Kong
Beijing
Singapore
(1) Which place has the lowest rainfall in July? Hong Kong / Beijing / Singapore / Canberra (2) Which place has high rainfall over the year? Hong Kong / Beijing / Singapore / Canberra
(1) Which places are wetter?
Hong Kong / Beijing / Singapore / Canberra
(2) Which places are drier?
Hong Kong / Beijing / Singapore / Canberra
Canberra
2. Jenny and her family are planning to have a ‘white Christmas’. Which of these places should they visit to have the best chance of seeing snow? 3. Work in groups. Among the four places, discuss which place you like the most in terms of its climate. Why?
19
3 What challenge does climate change bring to humans and the natural environment? 4. What place on the Earth is covered with snow and ice all year round?
1. What does ‘very hot weather’ mean? Why does the Hong Kong Observatory need to enhance the Very Hot Weather Warning service?
1
Arctic Ocean
Greenland
North Pole
2. Do you feel that it is getting hotter in Hong Kong every year? Do you have scientific evidence for this feeling?
northern hemisphere
Activity Booklet 6
2
Antarctica
3. Does the rise of temperature only happen in Hong Kong?
Australia is experiencing extremely hot weather and frequent bushfires ...
South Pole
southern hemisphere
5. There is a lot of snow and ice in the oceans and on the land of these places. How are these places affected by global warming?
20
1
2
ice cubes
ice cubes
6. Simulate the effect of melting sea ice and land ice on sea levels. Activity Booklet 7
sea ice
land ice
What effects does the melting of sea ice have on humans and animals?
Quick Check Melting sea ice / land ice causes sea levels to rise.
7. How may the rise of sea levels affect us?
1
2
Annual average sea level at Victoria Harbour (1954–2023)
1.8
1954–2023 increased by 31 mm every ten years
storm surge and high waves caused by a tropical cyclone
1.7
1.6
1.5
1.4
1.3
average sea level
1.2
height of sea level
1.1
reference level
1.0
1950
1960
1970
1980
1990
2000
2010
2020
Year
Source: Hong Kong Observatory website, HKSAR Government
8. What other effects does global warming bring?
1
2
3
21
4 How can we slow down global warming?
Humans use large amounts of fuels like gas and oil, and release large amounts of greenhouse gases like carbon dioxide. This blocks the heat from releasing from the Earth’s surface and causes a rise in the Earth’s temperature.
1. In the past hundreds of thousands of years, there had only been small changes in the amount of carbon dioxide in the Earth’s atmosphere. Why has the amount increased sharply in the past one hundred years?
Carbon dioxide content in the Earth’s atmosphere in the past 800000 years
Amount of carbon dioxide in the atmosphere (parts per million)
420 380 340 300 260 220 180 420 380 340 300 260 220 180
現今 Now 1958 1958 1911 1911
8070605040302010 0
萬年前 800 700 600 500 400 300 200 100 0
thousands of years ago
Source: The National Aeronautics and Space Administration website
1
2
3
4
industrial development
transportation
deforestation
bushfires
22
2. What is a carbon footprint? What activities or behaviour leave carbon footprints unnecessarily?
More to Explore Visit the ‘Polar Gallery' of Jockey Club Museum of Climate Change. Learn more about the seriousness of environmental problems, such as global warming and climate change.
waste electricity
use single-use utensils
waste food
travel by plane
shop excessively
To slow down global warming, we need to produce fewer greenhouse gases, such as carbon dioxide. Carbon footprints are the amount of greenhouse gases produced in some human activities. Many daily activities leave carbon footprints.
n i Link-up
Find out your carbon footprints and discuss how you can have a low-carbon lifestyle (in terms of clothing, food, housing, transport and entertainment). You can learn about this in Humanities lessons.
3. Which of these means of transport leaves fewer personal carbon footprints? Which one leaves more? Rank them and colour the footprints. (1= the fewest; 4 = the most)
1
2
3
4
23
4. Choose a topic on climate change (e.g. the causes of global warming, ways to slow down global warming and ways to reduce carbon footprints). Design a poster and share the information with your classmates.
on F o i l y L
Causes of Global Warming
課
Weather and climate of the Earth
condition of the atmosphere over a short period of time
average weather condition over a longer period of time
Climate change
Weather
Climate
Global warming
vary in different locations
Ways to slow it down
Causes
Effects
melting glaciers rising sea levels desertification
reduce carbon footprints
excessive use of coal, oil, etc.
24
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
Describe the Earth’s structure and its characteristics. State the main components of the Earth’s crust. Describe the characteristics and uses of different types of rocks. State the different types of soil, and identify the plants that are suitable to grow in them. Explain how the cycle of day and night is related to the Earth’s rotation. Explain why the northern and southern hemispheres have different seasons, and the relationship with revolution and the titled Earth's axis. Distinguish between weather and climate, and describe the climatic characteristics of different places. State the causes and effects of global warming, and list some ways to slow down global warming.
1
2
3
Skills and Processes
Create a model to simulate the Earth’s structure. Use tools to compare the characteristics of different rock samples. Test the components of soil and its drainage capacity. Through observation and recording, explore the changes in a shadow in the sunlight at different times of the day and find out the pattern. Read graphs and figures to study the weather conditions and climatic characteristics of different places. Create a model to simulate and test the effects of melting sea ice and land ice on sea levels.
1
2
3
Values and Attitudes
Cherish and protect rocks and soil.
1 3
Care about the changes in environment and climate, and reduce carbon footprints.
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:
25
26
1. What are the different natural environments on the Earth? 2. Imagine you are Jenny. In which natural environment do you want to have adventures? Why? 3. In which environments do you think are suitable for dogs to live? Why? Living Things and Environment
Unit 2
27
3 A. very cold and covered with ice all year round B. located at the boundary between land and water C. large temperature difference between day and night, dry with little rainfall D. very hot and rainy, with plenty of sunshine E. flat and open land, with distinct dry and rainy seasons 1. What characteristics do these natural environments have? Find information about them and write the correct letters in the . 1 What characteristics do different natural environments on the Earth have? What animals and plants are suitable to live there? 4 Animals, Plants and the Environment Living Things and Environment Unit 2
2
1
temperate grassland
wetland
28
2. Observe these pictures. In which natural environments do we find more plants or fewer plants? Why? 3. Based on the characteristics of these natural environments, in which of them do we find the most animal species? Why?
5
4
desert
tropical rainforest
polar region
29
Learn More
2 How do animals adapt to cold environments? 1. Observe the pictures. What characteristics do these polar animals have? Circle the correct answers. fur of polar bear
The Fur that Helps Keep Warm Unlike the fur of other mammals, the fur of polar bears is tube-shaped. This can trap more air for insulation and keep polar bears warm, helping them adapt to the very cold climate.
1
the centre is tube-shaped
structure of polar bear’s fur
polar bear
fat under walruses’ skin
outer layer of skin
2
fat under skin
walrus
thick / thin fur thin / thick layers of fat under the skin
30
2. How do these characteristics help polar bears and walruses adapt to cold environments? Circle the correct answers.
What other polar animals do you know of? Do they have these characteristics?
Animals living in polar regions have to keep themselves cool / warm , so many of them have thick fur and a thick layer of fat under their skin to maintain their weight / body temperature .
3. Some animals that do not live in polar regions use other ways to cope with the cold winter. Read this self-introduction of a hedgehog. Talk about the reasons for hedgehogs to have a deep winter sleep and their body condition during the sleep.
The chilly winter is coming. I know there will be no food when winter comes, so I eat enough food to build up a thick layer of fat under my skin before the deep winter sleep. During the sleep, I curl myself up like a ball to reduce heat loss. I also lower my body temperature, and reduce the frequency of my breathing and heartbeat. All these help reduce energy consumption.
hedgehog
What animal hangs itself upside down during its deep sleep in winter?
4. Besides having a deep winter sleep, how else do animals cope with cold environments?
31
1. What challenges do animals living in a hot and dry environment face? 2. These four animals live in the hot and dry desert. How do they adapt to the environment? Write the correct answers on the . 3 How do animals adapt to hot and dry environments?
My long and thick can block the wind and sand. My wide and soft feet allow me to walk on easily.
1
hump
camel
32
2
My sharp claws allow me to dig holes and hide in the underground.
meerkat
My hard and waterproof shell allows me to pull my head and limbs inside it when it is hot outside to reduce
loss.
I hide in a cave in the
3
and look for
food at
.
4
African spurred tortoise
jerboa
3. Camels have humps. How can this help them adapt to the unique hot and dry environment in the desert? Look for information online. Which of these pupils do you agree with?
Humps can bring the fat of camels together so that other parts of their body can lose heat more quickly.
Humps store fat. It gives camels energy when there is a lack of food.
Humps store water. It allows camels to survive even when there is a lack of water.
Fred
Jenny
Cindy
33
4 How do plants adapt to different environments? 1. What are the characteristics of these natural environments? Read pages 28 and 29 again to find the answers. 2. Plants have different characteristics. How do these characteristics help them adapt to different environments? Write the correct letters in the . (The letters can be used more than once.)
A. reduce water loss D. support the trunk
B. get more sunlight E. absorb more water
C. store water
Plants in temperate grasslands
Plants in deserts
2
long and narrow leaves
thick stems
1
3
wide spreading roots
needle-shaped leaves
34
Plants in tropical rainforests
4
5
trees are tall
huge buttress roots
6
7
stems of climbing plants gain support from big trees to grow upwards
undergrowth with broad and dark green leaves
35
Mai Po Nature Reserve is recognised as a Wetland of International Importance. It attracts many birds to fly from the cold northern areas to spend the winter here every year. Observe this picture and talk about why the wetland environment can attract birds to spend the winter. 5 Why are the wetlands in Hong Kong important to birds?
Migration refers to the behaviour of birds moving back and forth between different places in response to the change of seasons. The birds do this to escape the cold, find food or reproduce.
Where is Mai Po Nature Reserve? Which organisation manages the reserve?
The mudflat in this wetland gives us rich food like fish and shrimps. That is why we fly to Hong Kong to spend the winter every year.
We have to fly several thousand kilometres to the south to spend the winter. We need a place to rest and eat along the way.
Eurasian wigeon
black-faced spoonbill
36
Reading to Learn
Science for You Read ‘Into the Mangrove Wetlands’ to learn about the features and ecology of mangroves. Appendix 1 More to Explore 1. Visit Mai Po Nature Reserve or the Hong Kong Wetland Park to observe what other animals and plants live there besides birds.
Besides providing food and habitat, the wetland is also a good place for birds to reproduce.
white-breasted waterhen
I fly to Hong Kong in spring and in autumn because it is warmer than the north.
2. Observe plants
inside and outside your school. Find plants that grow in different places, such as on the fences or in the cracks of the pavement. What features of these plants help them adapt to their living environments?
black-winged stilt
We have to keep quiet when we watch birds. Do not disturb them or damage their habitats.
Source: World Wildlife Fund Hong Kong
37
課
cold areas
adapt to
adapt to
Desert
migrate
adapt to
Natural environments
Wetland
Polar region
Temperate grassland
Tropical rainforest
adapt to
adapt to
38
5 Balance of Nature Living Things and Environment Unit 2
1 How are the different living things in the forest inter-related? 1. In the forest, a living thing eats another living thing
and at the same time it may become the food of another living thing. Look at the picture and answer these questions. (1) Which living things do not need to eat other living things to survive? (2) Which living things eat plants to maintain their lives? (3) Which living things need to hunt animals for food?
39
2. Read the information to learn about the different roles of living things in the natural environment.
4
absorb energy from sunlight to make food on their own Producers (plants)
3
1
Oh, I just knew that spiders eat other insects.
2
12
are predators that hunt other animals (prey) for food Meat-eating animals
11
9
eat plants and other animals Plant-and-meat- eating animals
10
13
40
Plant-eating animals eating animals eat only plants
6
5
7
Is there a relationship between the body size of an animal and whether it is plant-eating or meat-eating? Explain with examples.
8
Elephants eat grass, leaves and fruit.
3. Analyse whether the living things in the forest on page 39 are producers, plant-eating animals or meat-eating animals. 4. A food chain shows the feeding relationships between animals and plants in an ecological environment. Refer to this example and draw three other food chains in the forest on page 39.
Activity Booklet 8
Example
eaten by
eaten by
grass
deer
tiger
(producer)
(plant-eating animal)
(meat-eating animal)
Feeding means the process of how animals get their food. As food provides energy for living things, a food chain also shows the process of energy transfer from producers to plant-eating animals and then to meat-eating animals.
14
There are feeding relationships between living things, forming ‘food chains’. e
41
2 How are the different living things in the ocean inter-related? 1. Below are some animals and plants living in the ocean. Refer to the information and find out different food chains.
More to Explore What animals are mentioned in the Chinese idiom ‘The mantis stalks the cicada, not knowing that the big bird is behind’? Draw a food chain based on their relationships.
1
Floating plants absorb energy from sunlight to make food on their own.
2
3
Activity Booklet 9
Small fish and shrimps eat seaweed and floating plants.
Squid eat small fish and shrimps.
Reading to Learn Science for You Read ‘Beautiful and Important Coral Reefs’ to learn about how coral is important to marine ecology.
5
4
Appendix 2
Sharks are predators in the ocean. They hunt shrimps, squid, fish and mammals, such as seals and dolphins, for food.
Whales eat fish and squid.
2. Work in groups. Act as different sea animals to show the food chains in the ocean.
Some people say the energy of all living things comes from the Sun. Do you agree? Why or why not?
In different environments, members of food chains are different. Different food chains may also overlap. For example, both whales and sharks hunt squid for food. e
42
3 When the number of living things in a food chain changes, what will happen to the food chain itself? 1. In a food chain, which living things have the smallest number, producers, plant-eating animals or meat-eating animals? Why? 2. Look at the two situations below. How will the food chain change? Circle the correct answers.
Situation 1
Humans hunt a large number of wolves. What will happen to the number of rabbits? What will happen to the number of plants?
number of plants increases / decreases
number of rabbits increases / decreases
number of wolves increases / decreases
Situation 2
What will happen to the food chain on the grassland when people keep spraying insecticide?
number of plants increases / decreases
number of worms increases / decreases
number of birds increases / decreases
number of snakes increases / decreases
Humans use insecticide to kill harmful insects. However, the toxic substances of insecticide can transfer from insects to insect-eating animals (such as birds) and accumulate up the food chain, affecting the health of meat-eating animals (such as snakes) at higher levels.
43
Living things in nature depend on each other. Different kinds of meat-eating animals may hunt the same kind of plant-eating animals for food, causing competitions among animals. 1. Look at this picture, find out how meat-eating animals compete with each other and point out what food they compete for. 4 How do living things compete for resources in nature?
vulture
giraffe
cheetah
lion
… and … compete with each other. The food they compete for is …
antelope
44
More to Explore
2. Do plants compete with each other? In this thick forest, what do they compete for? Write the correct answers on the . 3. How do these plants survive in competition?
Look for information online or in the library. See how animals escape from predators.
1
1
2
Frogs have protective colours.
2
The weak stem climbs up another tree to grow upwards.
The whole plant grows on a tall trunk.
and
These two plants compete for
Sea urchins have spikes.
.
3
3
4
Leafy sea dragons know how to pretend.
Prop roots grow into the soil to support the extending branches.
Roots spreading over the soil to stabilise the growing tree.
The roots of these two trees compete for
to
support the whole tree.
45
2
5 How can we protect nature? 1. Imagine humans keep destroying the natural environment. What may happen in the end? 2. How should we protect the environment and wildlife? 1
ban the sale of protected wild animals and plants, or their products
do not feed wildlife
課
Food
compete for
Relationships between living things
Sunlight
Living space
Environmental pollution
depend on each other
affect
Human behaviour
Food chain
Hunting
producer (plant)
plant-eating animal
meat-eating animal
Forest
eaten by
eaten by
Ocean
eaten by
eaten by
eaten by
46
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
State the different natural environments on the Earth, and relate them with some common animals and plants. List some characteristics of animals which help them adapt to the environment. List some characteristics of plants which help them adapt to the environment. State how some animals behave to survive in their living environments. Describe the roles of different living things in a food chain. State how the change in the number of a kind of living things affects the food chain. Identify some common predators and their prey. Explain with examples that some living things compete with each other for resources in the ecosystem.
4
5
Skills and Processes
Draw a food chain based on the feeding relationships between living things.
5
Values and Attitudes
Appreciate living things’ abilities to adapt to different environments. Show respect for lives, care for animals and plants, and protect the ecological environment.
4 5
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
1. Why can animals and plants on the Earth grow endlessly? 2. What are the characteristics of dogs and rabbits? Why do the same species of dogs and rabbits have different fur colours? 3. Why are humans so similar, yet there are so few people in the world exactly the same? Continuation of Life
Unit 3
48
49
6 Reproduction and Heredity of Plants Unit 3 Continuation of Life 1 How do plants reproduce? 1. Imagine plants do not reproduce. How will this affect our lives?
1
2
2. Which parts do these plants use to reproduce? Through the hints from the photos, find related information and circle the correct answers. (There can be more than one answer.)
1
2
tomato
sweet potato
roots / stems / leaves / seeds
roots / stems / leaves / seeds
4
3
garlic
violet
roots / stems / leaves / seeds
roots / stems / leaves / seeds
50
3. Do you remember the life cycle of flowering plants? Tell your classmates. 4. Observe these pictures. What processes do flowers go through to produce fruits and seeds, and reproduce successfully?
Most flowering plants reproduce through the seeds in their fruits.
1
2
pollen
Pollination: The insect carries the pollen from the stamen of one flower to the pistil of another flower.
stamen
pistil
4
3
The ovary grows into a fruit and seeds develop in the fruit.
After the ovary receives the pollen, other parts of the flower wilt.
5
6
The seeds sprout.
The seeds are spread to other places.
51
5. How do flowers attract insects or animals to help spread their pollen?
What colour is the flower?
Why does the hummingbird fly near the flower?
2
1
6. What other ways do plants use to spread their pollen?
corn
flowers of corn
1. Seeds develop in fruits. Observe the pictures below and find out the similarities of these fruits. Circle the correct answers. 2 How do plants increase the number of their offspring?
1
2
kiwi fruit
dragon fruit
In these fruits, there are a few / many seeds.
52
3
4
lychee
mango
Although there is only one seed / are many seeds in each of these fruits, these trees produce a few / many fruits.
2. The pictures below show a papaya tree and a papaya fruit cut in half. Guess the number of seeds this papaya tree can produce.
seeds
1
2
papaya fruit
I guess this papaya tree can produce seeds.
3. Can you accurately guess the number of seeds this papaya tree can produce? Why or why not?
papaya tree
Many plants produce a small / large number of seeds or fruits to increase their success rate of reproduction. Quick Check
53
3 How do plants increase their offspring’s chances of survival? 1. Plants spread their seeds to other places to increase the reproduction rate and avoid competition among offspring. Observe these pictures to learn about the media that plants use to spread their seeds.
2
1
carried by flowing water
blown by the wind
by water
by wind
4
3
eaten by animals or stuck to animals’ bodies
shot out by its own force
by its own force
by animals
Activity Booklet 10 2. Observe the pictures below. What methods do the fruits of these plants use to spread their seeds? Give your answer based on the characteristics of these fruits.
2
1
white popinac
4
dandelion
3
coconut
hitchhiker plant
3. Make a model of a dandelion fruit to explore the relationship between the weight of fruits and their falling speed. Activity Booklet 11
54
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