Teacher’s Notes
Outline the learning aims of the section.
Teacher’s Notes
Start the lesson by showing students the picture on the slide.
Encourage students to answer and contribute to the discussion.
Ask: Why do people use ships and boats?
Expected answer: Answers may vary. People use ships and boats for travelling, for carrying things, for fishing, etc.
Ask: Large ships have a huge weight. Why are they able to float on water?
Expected answer: Answers may vary. Students may say that there is an upthrust that balances the weight of the ship.
Teacher’s Notes
Refer to page 97 of the Student’s Book.
Ask: What is weight? Is it the same as mass?
Expected answer: Answers may vary.
Teaching Strategy: Take note of what students know at this stage. This will help you to teach the concepts that students are not familiar with.
Teacher’s Notes
Show students the picture on the slide.
Have students recall what the mass of an object is.
Ask: What is mass?
Expected answer: The amount of matter an object is made up of
Ask: The two balls in the picture are of the same size. The green ball is hollow but the red ball is not. Do you think they have the same mass?
Expected answer: No. They have different amounts of matter so they have different masses.
Ask: How do we measure the mass of an object?
Expected answer: Using a measuring scale, in kilograms or grams
Teacher’s Notes
Ask: Which has a greater mass — 1 kg of feathers or 1 kg of gold?
Expected answer: Answers may vary. For example, my mass remains constant as the amount of matter in my body remains unchanged, but my weight will decrease as the gravity on Mars is weaker than the gravity of Earth.
Teacher’s Notes
Show students the picture on the slide.
Ask: What will happen to the ball after it is thrown up in the air?
Expected answer: It will come down.
Ask: Why do objects fall onto the ground when they are released from a height or thrown up?
Expected answer: Gravity pulls the objects down, towards the centre of Earth.
Ask: Why do you think an object like a pencil always fall onto the ground when it slips through our fingers?
Expected answer: Answers may vary. For example, students may say that the Earth pulls the object down, etc. It is because there is a special pulling force called gravity on the Earth that pulls all objects towards the centre of the Earth.
Refer students to the picture of the two balls on the previous slide.
Ask: If the red ball has a greater mass, will the balls have the same weight?
Expected answer: No. The green ball will have a greater weight.
Ask: Do you think each ball would have the same weight on the Moon and on Earth?
Expected answer: Answers may vary.
Ask: Do you think each ball would have the same mass on the Moon and on Earth?
Expected answer: Answers may vary.
Explain to students that gravity differs on different planets and on the Moon, and gravity affects the weight of an object but not its mass.
Teacher’s Notes
Show the questions to students.
Ask: Why does an apple fall straight down from a tree, and not upwards or sideways? Does the size of an object determine how much gravity affects it?
Inform students that they will find the answers in the video they will be watching.
Use the MCE Cambridge app to launch the video on page 98 of the Student’s Book that explains the effect of gravity on Earth.
Play the video for the class.
After watching the video, return to this slide and discuss the answers to the questions.
Expected answers:
The gravity of Earth acts on the apple. It pulls the apple down to the ground.
Without gravity, all things will float off into space.
Teacher’s Notes
Use this slide in normal mode instead of presentation mode.
Ask students to identify the differences between mass and weight.
Drag the descriptions to the correct boxes.
Answers:
Mass — a measure of the amount of matter, can be measured in kilograms or grams, does not depend on gravity
Weight — a measure of the effect of gravity, measured in newtons, depends on gravity
Teacher’s Notes
Get students to answer the question.
Answer:
My mass will remain the same but my weight will be less on Mars than on Earth.
Teacher’s Notes
Outline the learning aims of the section.
Teacher’s Notes
Start the lesson by showing students the picture on the slide.
Ask: What types of forces are acting on the bicycle?
Expected answer: Answers may vary. Students may be aware that forces such as gravity, the push from the pedalling and friction are acting on the bicycle.
Ask: The bicycle is moving at a constant speed. Do you think that all the forces acting on it are equal?
Expected answer: Answers may vary. Some students may say ‘yes’ and some may say ‘no’.
Teacher’s Notes
Refer to page 100 of the Student’s Book.
Ask: What forces act on an aeroplane in flight?
Expected answer: Answers may vary.
Ask: How do the forces affect the motion of the aeroplane?
Expected answer: Answers may vary.
Teaching Strategy: Take note of what students know at this stage. This will help you to teach the concepts that students are not familiar with.
Teacher’s Notes
Go through with students the effects of forces on stationary and moving objects.
Ask: If the two forces acting on the box are the same, will the box move or remain at rest?
Expected answer: The trolley will remain at rest as the two forces are the same and will balance each other.
Ask: If the two forces acting on the box are different, will the box move or remain at rest?
Expected answer: The trolley will move if one of the forces is greater than the other as the two forces are unbalanced.
Teacher’s Notes
Use this slide in normal mode instead of presentation mode.
Ask students to identify the forces acting on the aeroplane.
Drag the labels to the correct boxes.
Answers:
drag
lift
gravity
thrust
Discuss with students the effects of the forces on the motion of the aeroplane.
Ask: What will happen to the motion of the aeroplane if all the forces are balanced?
Expected answer: It will be flying straight, level and at the same speed.
Ask: What will happen to the motion of the aeroplane if the thrust is greater than the drag?
Expected answer: It will speed up.
Ask: What if the thrust decreases but is still greater than the drag?
Expected answer: The aeroplane will move slower than before.
Ask: How do the forces act if the aeroplane rises?
Expected answer: The lift is greater than the gravity.
Teacher’s Notes
Ask: What forces are always acting on an object when it is at rest?
Expected answer: Normal force and gravity
Teacher’s Notes
Get students to answer the questions.
Answers:
Balanced
Unbalanced, speed, direction
Teacher’s Notes
Outline the learning aim of the section.
Teacher’s Notes
Start the lesson by showing students the picture on the slide.
Have students recall what they have learnt in Stage 5 about forces that act on an object in water.
Ask: What is the force that keeps the duck from sinking in water?
Expected answer: Upthrust
Teacher’s Notes
Ask: Can we change an object that sinks to make it float?
Expected answer: Answers may vary. For example, students may say that we can change the shape of the object.
Teaching Strategy: Take note of what students know at this stage. This will help you to teach the concepts that students are not familiar with.
Teacher’s Notes
Have students recall that upthrust is the upward force that helps keep an object from sinking in water.
Refer students to the picture on the slide.
Ask: Which has a greater mass — the wooden ball or the iron ball?
Expected answer: The iron ball has a larger mass.
Ask: How does the mass of an object affect if the object floats or sinks?
Expected answer: If an object has a larger mass, it will have a larger weight. When the weight is equal to or less than the upthrust, the object floats. When the weight is greater than the upthrust, the object sinks.
Ask: What can you do to make the iron ball float?
Expected answer: Answers may vary. For example, the iron ball can be melted and changed into a different shape with a larger surface area.
Teacher’s Notes
Use this slide in normal mode instead of presentation mode.
Ask students to identify the shape that will float.
Drag the correct shape to the box.
Answer:
aluminium boat
Explain to students that if the surface area of an object increases, the size of the upthrust will increase and the object is likely to float.
Teacher’s Notes
Remind students that an object that is in water has upthrust and weight acting on it.
Ask: Does an object weigh less in water than in air? Why?
Expected answer: Any object that is in water has upthrust pushing up against gravity, so it will weigh less in water than in air.
Teacher’s Notes
Use this slide in normal mode instead of presentation mode.
Drag the ticks to the correct boxes.
Answers:
False
False
