Page 5 - 新思维科学学生用书9 样章
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How to use this book
How to use this book
Photosynthesis and the
1
carbon cycle
This book contains lots of different features that will help your learning. These are explained below.
1.1 Photosynthesis
3 Forces and energy 3 Forces and energy
In this topic you will:
This list sets out what you will learn in each • 3.4 Moving from hot to cold
3.3 Conservation of energy
practise using the word equation for photosynthesis
• learn what photosynthesis is, how it happens and why it is important.
topic. You can use these points to identify In this topic you will:In this topic you will:
discover that thermal energy always transfers from hotter places to colder places
the important subjects for the topic. • Getting started • • learn that energy cannot be created or destroyed
understand what is meant by heat dissipation.
understand that because energy is conserved, there is no increase or decrease
•
Look at the pictures of the young maize (corn) plants.
in energy
The plants on the left have been given light, but the
ones on the right have not had light.
Getting started • understand that thermal energy is dissipated from hotter places to colder places.
Key words
You may also be able to look at some actual plants that
This contains questions or activities to help find Work in groups. colder
have been grown in the light and in the dark.
Getting started
Imagine you are in a hot room. It is colder outside than inside. hotter Key words
With a partner, make a list of the differences you can
out what you know already about this topic. When someone opens a window, the room feels colder. conserved
Thermal is an energy store. List as many other types of
1
see between the two sets of plants.
Discuss what happens in terms of thermal energy to make the created
energy store as you can remember.
Suggest what has caused these differences.
room colder. 2 Choose two of your energy stores. Describe how the destroyed
energy can be changed between these energy stores.
Important words are highlighted and 3 Describe what is meant by dissipated energy. system
explained in the text. You will also find
Key words
definitions of all these words in the Glossary chlorophyll light intensity photosynthesis
and index at the back of this book. 3.1 Density
Activity 3.1.1
Densities of some regular objects
In this activity, you will calculate the densities of some different materials, using
You will have the opportunity the mass and volume of regular objects.
6 You will need:
to practise and develop the new • a balance, a calculator, a ruler that can measure in millimetres, some regular
objects made from different materials.
skills and knowledge that you 02-SJ00079351 新思�科学 学生用�9（P6-45）-2校_SoD.indd 6 2022/7/7 下午 04:44:34
Method
1 Measure the length, width and height of each object. You should measure to
learn in each topic. Activities will the nearest 0.1 cm.
2 Calculate the volume of each object in cm 3 .
involve answering questions or 110 3 Measure the mass of each object in grams. Remember to check that the
balance is reading 0.0 g before you place the material on the balance.
104
4 Calculate the density of each material using the volumes and masses that you
completing tasks. measured.
3 Forces and energy
5 Record your results in a table.
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Questions
1 Think like a scientist
The density of water is 1.0 g/cm 3 . Use this value and your calculated densities
to predict which materials will float and which will sink in water. If you have time,
Densities of irregular objects
you could test these predictions.
In this investigation, you will calculate the densities of irregular objects.
2 Explain the importance of making sure the balance is reading 0.0 g before you
This provides an opportunity for you You will need:
place the material on the balance.
a balance, measuring cylinders of various sizes, water, a calculator, small
3 • Some blocks of material may be old and slightly damaged,
irregular objects that will sink in water and will fit inside the measuring
to practise and develop practical skills such as the one shown in the diagram.
a cylinders.
Explain why your calculated value for the
volume of these damaged objects may not
with a partner or in groups. Safety be correct.
Do not drop heavy objects into glass measuring cylinders; either use a plastic
Explain whether the masses of these damaged
b
measuring cylinder, or hold the glass measuring cylinder at an angle, so that the
objects will be correct.
object slides down slowly.
c Suggest how any differences in volume and mass would affect the
Method calculated value of density.
1 Measure the mass of each object in grams. Remember to check that the
balance is reading 0.0 g before you place the object on the balance.
2 Use the displacement method to calculate the volumes of your objects in cm 3 .
3 Calculate the density of each object using the volumes and masses that you
measured.
4 Record your results in a table. 93
Questions
4 1 Explain why you should read the volume on a measuring cylinder with your eye
at the same level as the surface of the liquid.
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2 Explain how you would use the displacement method to calculate the volume
of an object that floats in water. Remember that the displacement method only
gives the correct volume of an object that is completely under the water.
3 Explain how you would use the displacement method to calculate the volume
of an object that sinks in water but is too big to fit in a measuring cylinder.
4 Sofia and Zara are calculating the densities of irregular objects. Zara calculates
the density of a small toy made from wood to be 5.27 g/cm 3 . Sofia says
this result is anomalous. Explain whether this result is likely to be correct or
anomalous.
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