BASIC SCIENCE AND TECHNOLOGY
SMASE – ASEI PDSI METHOD
THEME – LEARNING ABOUT OUR ENVIRONMENT
PREVIOUS LESSON – Meaning, Types and Effects of Force (Primary 6)
TOPIC: FRICTIONAL FORCES
1. Meaning of Frictional Force
2. Effects of Frictional Force
3. Advantages and Disadvantages of Frictional Force
4. Methods of Preventing Frictional Force
By the end of the lesson, the pupils should have attained the following objectives (cognitive, affective and psychomotor):
1. explain frictional force as the resistance between two surfaces in contact;
2. mention instances of the application of frictional force in daily activities;
3. state the advantages and disadvantages of friction.
Pull and push
The teacher will teach the lesson with the aid of palms. Stones and pebbles, balls bearings, matched, knife, floor, water, Vaseline, sand paper, glass, oil, soapy water.
METHOD OF TEACHING – Choose a suitable and appropriate methods for the lessons.
Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons.
1. Scheme of Work
2. 9 – Years Basic Education Curriculum
3. Course Book
4. All Relevant Material
5. Online Information
Meaning and Effects of Frictional Forces – ASEI PDSI METHOD (Primary 6)
Third Term Scheme of Work and Plan Lesson Note for Basic Science and Technology Primary 4, Primary 5 and Primary 6 Links
CONTENT OF THE LESSON
LESSON ONE – INTRODUCTION
To stop a moving object, a force must act in the opposite direction to the direction of motion. For instance, if you push your book across your desk, the book will move. The force of the push moves the book.
As the book slides across the desk, it slows down and stops moving. The force that opposes the motion of an object is called friction.
MEANING OF FRICTION
Friction is the force that opposes the motion of an object. Friction can slow down or stops any moving objects.
EFFECTS OF FRICTION
What effect does friction force have on motion?
1. It opposes the motion of all objects.
2. It slow down any moving objects.
3. It counteracts the acceleration of an object.
4. It prevents surfaces from sliding against each other.
5. It causes objects to accelerate.
LESSON TWO – ADVANTAGES OF FRICTION
Friction plays a vital role in our daily life. Without friction we are handicap.
1. It prevents slipping while walking.
2. It stops cars from moving.
3. We cannot fix nail in the wood or wall if there is no friction. It is friction which holds the nail.
4. A horse cannot pull a cart unless friction furnishes him a secure Foothold.
DISADVANTAGES OF FRICTION
Despite the fact that the friction is very important in our daily life, it also has some disadvantages like:
1. The main disadvantage of friction is that it produces heat in various parts of machines. In this way some useful energy is wasted as heat energy.
2. Due to friction we have to exert more power in machines.
3. It opposes the motion.
4. Due to friction, noise is also produced in machines.
5. Due to friction, engines of automobiles consume more fuel which is a money loss.
LESSON THREE – METHODS OF REDUCING FRICTION
There are a number of methods to reduce friction in which some are discussed here.
1. Use of Lubricants
The parts of machines which are moving over one another must be properly lubricated by using oils and lubricants of suitable viscosity.
2. Use of Grease
Proper greasing between the sliding parts of machine reduces the friction.
3. Use of Ball
Bearing In machines where possible, sliding friction can be replaced by rolling friction by using ball bearings.
4. Design Modification
Friction can be reduced by changing the design of fast moving objects. The front of vehicles and airplanes made oblong to minimize friction.
WEEKLY ASSESSMENT – As stated in performance objectives or lesson evaluation.
To deliver the lesson, the teacher adopts the following steps:
1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the pupils some questions;
2. Guides pupils to demonstrate friction.
3. Shows the effects of friction for pupil to observe.
Pupils’ Activities – Rub the following surfaces together and describe their experiences: their palms, a rough surfaces against a smooth one, two smooth surfaces.
Pupils’ Activities – Describe what happens when: they rub their palms together, rub two stones together, strike two tones together, and they strike a sharp edge of a machete against a stone.
4. Plans and takes the class on visits to places such as metal fabrication workshop etc. for pupils to observe friction.
Pupils’ Activities – Use different lubricants, ball bearing, rollers to reduce friction.
Pupils’ Activities – Identify and discuss the effect of friction on the machines and tools found in the workplaces visited.
- To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson (magnetic force).
1. define friction;
2. state two instance of the application of friction in daily activities;
3. mention two advantages and disadvantages each of friction.