Science Year 4 Textbook Notes
Scientific Skills
Science process skills help us to scientifically understand objects and our surroundings.
Examples
Observing: Noticing the increase of rubbish each day and its unpleasant smell
Classifying: Sorting rubbish according to its type (paper, metal, plastic, glass).
Measuring and Using Numbers: Weighing cans before selling them (e.g., aluminium cans at RM4.00 per kilogram).
Making Inferences: Understanding that food leftovers will rot in the soil.
Predicting: Estimating earnings from selling aluminium cans (e.g., predicting RM8.00).
Communicating: Discussing ways to dispose of the rubbish.
Using Space-Time Relationship
Using space-time relationship involves describing changes in situations or phenomena based on changes in parameters over time (location, direction, shape, size, volume, weight).
Example: A popsicle changes its shape and becomes smaller in size when placed under sunlight for 20 minutes.
The relationship between space and time: As time increases, the shape of popsicle becomes irregular and decreases in size.
Interpreting Data
Interpreting data is a skill to give rational description about objects, events or patterns from collected data。
Examples
Bird Feeder Data Interpretation: identifying the numbers of birds visits different bird feeders everyday. For example, "Bird feeder B was the least visited by the birds" or "Most birds flocked to bird feeder A."
Pie chart: Mode of Transportation Interpretation: Pupils riding bicycle and walking are similar. The main mode of transport is by bus.
Bar chart: Toy Car Distance Interpretation: Toy car A traveled the furthest.
Classification chart: Animal Reproduction Method Interpretation: Crocodile, fish, and chicken lay eggs, while elephant, cat, and wolf give birth.
Defining Operationally
Defining operationally is a skill to define a concept by stating what can be carried out and observed.
Example
The operational definition of the ability of the material to absorb water is the volume of water left in the beaker.
The operational definition of the growth of a green bean plant involves recording the number of leaves and the height of the seedling.
Controlling Variables
Variables are factors that can change in an investigation.
Manipulated variable: A variable that is changed in an investigation
Responding variable: A variable that is observed in an investigation
Constant variables: Variables that remain constant.
Making a Hypothesis
Making a hypothesis is a skill to make a general statement that can be tested about the relationship between the variables in an investigation.
Based on the example, as the number of stirs increases, the time taken for the sugar to dissolve completely decreases.
Experimenting
Experimenting is a skill to plan and conduct an investigation to test a hypothesis by collecting and interpreting data to make conclusions from the investigation.
Steps:
Identifying the problem and making a problem statement
Making a hypothesis
Controlling the variables
Listing the apparatus and materials
Planning the steps
Collecting and interpreting data
Testing the hypothesis
Making a conclusion
Writing a report
Humans
Humans breathe to survive. During inhalation, air is taken into the lungs. During exhalation, air is expelled from the lungs. The lungs are the organs involved in human breathing.
Human Breathing Process
Other than the nose, air can also enter the lungs through the mouth.
During inhalation the oxygen enters the nose, then passing through the trachea, exchange of gases take place in the lungs.
During exhalation the carbon dioxide is carried out of the lungs, then passing through the trachea, released through the nose.
Content of Oxygen and Carbon Dioxide During Breathing
Inhaled air contains more oxygen compared to exhaled air.
Exhaled air contains more carbon dioxide compared to inhaled air.
Chest Movement During Breathing
During inhalation the chest moves upwards
During exhalation the chest moves downwards
Rate of Breathing
The rate of breathing is the number of upward and downward chest movements in one minute.
The rate of breathing depends on the type of activity that is carried out.
Situations That Affect Breathing
Haze is dry air containing various gases, dust, and floating particles in the atmosphere which causes low visibility and it is unhealthy for humans.
Air in a clean environment ensures that humans breathe better.
Excretion and Defecation
The human body produces different waste products such as urine, sweat, faeces, carbon dioxide, and water vapour.
The removal of waste products from the body is called excretion.
The removal of faeces through the anus is called defecation.
Organs and Their Products of Excretion
Excretion takes place in excretory organs
Lungs: Release carbon dioxide and water vapour.
Skin: Excretes sweat.
Kidneys: Excrete urine.
Importance of Excretion and Defecation
It is important to get rid of the products of excretion and faeces, Doctor, I find it difficult to urinate. Usually, if a person has difficulty to urinate, there may be a possibility of having kidney stones.
When your faeces is hard, it will be difficult for you to defecate. This is known as constipation.
Response to Stimuli
Humans respond to changes in their surrounding environment. The surrounding environment can change. The changes are known as stimuli.
The action taken towards the stimulus is called response.
The sensory organs of humans receive stimuli such as light, smell, sound, taste, and touch.
Importance of Response
Humans respond when the sensory organs receive stimuli.
Humans need to respond to stimuli:
to avoid injury
to save oneself
to obtain information and to communicate
Habits that Disrupt Human Response
Alcohol consumption, glue sniffing, and drug abuse have serious consequences on human lives. These habits can disrupt human response to stimuli.
Alcoholic drinks can cause intoxication.
Glue is a chemical substance that can cause hallucination and addiction to those who sniff it.
Drugs can be used as medicine. However, abuse of drugs such as cough syrups or ecstasy pills can cause hallucinations, blackouts, and addiction.
Animals
Animals breathe using organs such as lungs, gills, moist skin, and spiracles.
Spiracles are breathing pores found in the cuticles of insects (outer layer of the body).
Classification of Animals Based on Their Breathing Organs
Animals can be classified according to their breathing organs, which are lungs, gills, moist skin, and spiracles.
Living on Land and in Water
Some animals have more than one breathing organ such as frogs. They can breathe through their lungs and moist skin.
Vertebrates and Invertebrates
Vertebrates are animals with backbones.
Invertebrates are animals with no backbones.
Specific Characteristics of Vertebrates
Vertebrates can be classified as mammals, reptiles, amphibians, birds, and fish.
Mammals
Breathing organ: lungs
Method of reproduction: give birth
Body covering: fine hair
Habitat: on land
Amphibians
Breathing organs: lungs and moist skin
Method of reproduction: lay eggs
Body covering: moist skin
Habitats: on land and in water
Fish
Breathing organ: gills
Method of reproduction: lay eggs
Body covering: scales
Habitat: in water
Birds
Breathing organ: lungs
Method of reproduction: lay eggs
Body covering: feathers
Habitat: on land
Reptiles
Breathing organ: lungs
Method of reproduction: lay eggs
Body covering: scales or hard shell
Habitat: mostly on land
Plants
Plants also respond to stimuli, such as water, gravity, light, and touch.
Plant Responses to Stimuli
Roots respond and grow towards water and gravitational pull.
Shoots respond and grow towards light.
Leaves of some plants respond to touch
Photosynthesis
Plants need sunlight, chlorophyll, carbon dioxide, and water for photosynthesis.
During photosynthesis, chlorophyll absorbs sunlight and converts water and carbon dioxide into glucose and oxygen.
Importance of Photosynthesis to Living Things
Plants constantly carry out photosynthesis to enable them to produce their own food.
Photosynthesis is important to living things because it enables plants to provide food, to produce oxygen for breathing, and also to maintain the balance of gas composition in the air.
Properties of Light
Light travels in a straight line.
Shadows are formed when a moving light is obstructed by an object.
The size of the shadow becomes larger if the distance between the light source and the object is shorter.
The orientation of the object and the position of the light source affect the shape of the shadow.
Reflection of Light
When we look in the mirror, we can see our image. This is due to the reflection of light.
Applications of Reflection of Light
Mirror, periscope, dental mirror used in our daily lives showing that light can be reflected. Two mirrors in the periscope reflect the obstructed light from an object to the eyes of the observer.
Ray Diagram
When the light is directed onto a flat, smooth surface like a mirror, the light is reflected.
Refraction of Light
When light travels through two different mediums, the direction of light will change. This is called refraction of light.
Formation of a Rainbow
When the sun shines on the rain droplets, the light will be refracted? This will form a rainbow.
Importance of Properties of Light in Daily Life
If light does not travel in a straight line, cannot be reflected and refracted to enable to see in the surrounding.
Sound
Sound is produced by vibrations.
Sound can be produced through blowing, knocking, plucking, bowing, and clapping.
Sound Travels
Sound travels in all directions.
Sound Can Be Reflected
When a sound hits a hard surface, it is reflected.
Phenomena of Reflection of Sound
Echo is a sound produced when a sound is reflected on a hard surface.
Sonar is a technology that reflects ultrasonic sound to detect objects in water.
Ultrasound is a sound that humans cannot hear but can be heard by animals such as bats, dolphins, and whales to navigate and detect the location of their prey.
Useful and Harmful Sounds
Sound has many effects in our lives. Musical sound can be entertaining. Sound allows us to communicate. The siren of the ambulance indicates an emergency alert,
Frequent or excessive loud noises can cause hearing problems. The unit for measuring the loudness of sound is decibel (dB). Loud noise that exceeds 85 dB can damage our hearing.
Reducing Sound Pollution
Loud or unwanted sound can be reduced. Airport ground staff use ear protectors to prevent ear damage from the excessive aircraft noise.
Sound absorbers like carpets, curtains, and windows reduce sound vibration.
Energy
Energy is the ability to do work. Energy can be obtained from a variety of sources.
Energy and Their Sources
Biomass is a substance from plants or animal faeces used to produce fuel and generate electricity.
Forms of Energy
Solar energy, light energy, heat energy,electrical energy,kinetic energy, nuclear energy, potential energy, chemical energy and sound energy.
Transformations of Energy
Energy can be transformed from one form to another. The following equations shows how it transforms from one form to another:
Riding a bicycle: Chemical energy → Kinetic energy
Switching on a television: Electrical energy → Light energy + Sound energy
Lighting a fire: Chemical energy → Heat energy + Light energy
Energy Cannot Be Created or Destroyed
Energy cannot be created or destroyed but can be transformed.
Renewable and Non-renewable Energy Sources
Energy sources can be classified into renewable and non-renewable energy sources.
A source of energy that can be generated continuously is called Renewable energy.
Energy sources that are limited and cannot be regenerated is called Non-renewable energy
Using Energy Wisely
In order to ensure that we have sufficient energy sources in the future, we need to use the energy wisely.
Materials
The objects are made from a variety of basic sources such as plants, animals, petroleum, and rocks
Basic Sources of Materials
Materials from plants, animals, rocks and petroleum
Properties of Materials
Properties of materials are water absorbent and waterproof, float and sink, conduct electricity ,ability for light to pass through, conduct heat, elastic.
Applications of Properties of Materials
Knowledge of the properties of material is important in designing an object.
Choosing a suitable type of material will ensure proper functioning of the created objects.
Choosing Types of Materials to Invent an Object
An object is invented based on the suitability of the materials to the function of the object.
Earth
All objects that are around us are pulled towards the centre of Earth by a force known as the gravitational pull on Earth. Gravity or gravitas in Latin means weight.
Gravitational Pull on Earth
The gravity of Earth is the force that pulls objects towards the centre of Earth.
Without the gravitational pull on Earth, all objects will float in the air.
Importance of Gravitational Pull on Earth
The gravitational pull on Earth is important for the objects to remain in their positions.
Rotation and Revolution of Earth
Earth rotates on its axis and at the same time revolves in its orbit around the Sun.
Direction and Duration of Rotation and Revolution of Earth
Earth rotates on its axis in an anticlockwise direction.
Revolution of Earth around the Sun in its orbit is from West to East and in Anticlockwise direction.
One complete rotation takes 24 hours or one day.
One complete revolution takes one year or days.
Effects of the Rotation of Earth on Its Axis
The rotation of Earth causes several phenomena to happen.
Occurrence of day and night.
The Sun seems to change its position.
Changes in the length and direction of the shadow.
Machines
A lever is used to lift or pry out an object. The lever consists of three parts; load, fulcrum, and force.
Lever
Load is the weight of an object.
Fulcrum is a point on a beam that functions to support and balance the beam.
Force is the push and pull action which gives effects to an object.
Relationship between Load, Fulcrum, and Force
The closer the load from the fulcrum, the lesser the force that is needed to lift the load.
Simple Machines
The simple machine is a tool that helps us to work more easily and quickly.
Each simple machine has its own specific use.
Types of Simple Machines:
Wheel and axle
Screw
Gear
Pulley
Inclined plane
Wedge
Uses of Simple Machines to Solve Problems
The more the number of simple machines used, the easier and faster the work can be done.
Complex Machines
A tool that consists of a combination of more than one simple machine is a complex machine.
Sustainable complex machines are machines that have sustainable characteristics such as durability, not easily damaged, profitable, does not harm the environment, as well as are easy and safe to use.