Thursday, 20 October 2011

Wednesday, 19 October 2011

Worksheet 14

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Activity:

Tick the correct answers.

Friction can be reduced by:

using wheels( )

using anti-slip mats ( )

using air cushions ( )

using talcum powder ( )

using oil, wax or grease ( )

sanding surfaces to make them smooth ( )

using rollers or ball bearings ( )

using patterns on soles of shoes ( )

using rubber pads or knobs( )

using engine oil to lubricate engines ( )

Evaluation:

Circle the correct answers.

1. Which of the following slows down the speed of a moving car?

I. The tread on tyres

II. Lubricating the car engine

III. A rough and dry road surface

IV. A wet and slippery road surface

A. I and II C. II and IV

B. I and III D. III and IV

2. Which of the following surfaces produces the greatest friction when an object moves across it?

A. Wet surface

B. Oily surface

C. Rough surface

D. Slippery surface

3. Which of the following items can help to reduce friction?

I. Lubricants

II. Air cushion

III. Rubber pads

IV. Ball bearings

A. I, II and IV C. II, III and IV

B. I, II and III D. I, II, III and IV




Choose True or False for the statements below.

1. Friction can be increased by smoothening the surfaces in contact.

True

False

2. Friction is reduced by using rollers and ball bearings.

True

False

3. Talcum powder is used to reduce friction between carom disks and the carom board.

True

False

4. Without friction, we can light up a match.

True

False

5. Rubber materials have less friction than metal materials.

True

False

Lesson 14

Lesson 14: Ways To Increase Or Reduce Friction.


Learning Objective


Analysing friction.

Syllabus Correlations

· Theme: Investigating force and energy.

· Learning Area: Force

· Learning Objective: Analysing friction

Learning Outcomes:

By the end of the lesson, pupils should be able to:

· describe ways to reduce friction;

· describe ways to increase friction.

Concept(s) Introduced:

· Friction and be increase or reduce

Skills Covered:

· Observing, classifying, making inferences, interpreting data, making conclusions, comparing and contrasting.

Vocabulary/ New Words:

· Rollers, ball bearings, lubricants, grease, door hinges, engine oil, cushion, talcum powder, polished smooth, prevent skidding, rougher surfaces, patterns, soles of shoes, tread of tyres, better grip, slippery surfaces, handles of rackets, golf clubs, anti-slip mats, prevent slipping, streamlined shape, conveyor belt.

Value(s) Incorporated:

· Having an interest and curiosity towards the environment.

· Being diligent and persevering.

· Realising that science is a means to understand nature.

· Thinking rationally

Materials Needed:

- oil, talcum powder, grease, roller, ball bearing.

Point(s) to Note:

- We increase the friction when it is useful in our daily live.

- We reduce the friction when it brings unproductive effects to us.


Teaching Strategies

Set Induction

Teacher gives the problems based on the video clip: car overheats and slippery road. Ask pupils to give suggestion on how to solve these problems. Teacher plays the Introduction component. Brainstorming the pupils those problems occurs because of friction. Let the pupils give solutions on friction. Encourage the pupils to put up their hands to answer the questions. Teacher uses the video to explain the problems caused by friction, effects of friction and solutions to overcome friction.

Component: Introduction

Step 1

Teacher gives a scenario why we need to reduce friction. Teacher plays the video clips concerning ways to reduce friction. Teacher pause the video clip that related to luggage for a while, ask pupils ways to overcome friction. Continue to play the video, pupils will get the idea on ways to reduce friction. Teacher gives the five ways to reduce friction. Allow pupils to suggest some other ways to reduce friction. Ask pupils list them down on a piece of paper and present it to the class.

Component: Content 1

Teacher gives a scenario why we need to increase friction. Teacher plays the video clips concerning ways to increase friction. Teacher pause the video clip that related to car skidding for a while, ask pupils ways to overcome friction. Continue to play the video, pupils will get the idea on ways to increase friction. Teacher gives the three ways to increase friction. Allow pupils to give some other ways to increase friction. Ask pupils list them down on a piece of paper and present it to the class.

Component: Content 2

Step 2

In this activity, pupils need to choose ways to reduce friction. There are ten options for pupils to choose. Pupils need to think rationally before they choose the answers.

Component: Activity

Step 3

There are five questions in this component cover the learning outcomes. For Questions 1 to 3, allow pupils choose the correct answers for the objective questions. Q4 contains of drag and drop, pupils need to drag and drop the correct answers for the questions appeared. Q5 consists of true or false questions. Pupils need to identify whether the statements are true or false.

Teacher can use the evaluation that will assess the pupils’ understanding of the lesson.

Component: Evaluation

Step 4

Teacher plays the Extension component about excess friction means that extra fuel must be used to power the vehicle. In other words, petrol is being wasted because of the friction. Guide pupils to understand that how petrol can be saved as we drive in highway with window closed.

Component: Extension

Conclusion

Teacher concludes the lesson by playing this component to further reinforce understanding of the lesson. Teacher asks pupils to describe ways to reduce or increase friction. Prompt pupils to list all of them in the class.

Component: Summary