Learning Objectives - Content

• Understand that PUSH & PULL are forces & to be able to arrive at the definition of the term 'force'
• To establish a relationship between force and state of motion (activity)
• To investigate the effect of forces on 'State of Motion, direction, shape, speed'
• To know of the different types of forces
• To develop scientific skills such as observation, hypothesizing (predicting), articulation of scientific understanding with evidence

Prerequisite Knowledge

• Different ways of making an  object move and stop
• Estimate/ articulate the direction of movement of objects
• Estimate/ compare  the  relative  speed of movement of objects

ENGAGE

These activities can be conducted as group/pair/individual/whole  class activities.

Activity: This is a whole class activity

1. A soft smiley ball is tied to a string and hung from the top in the classroom
2. The students are asked to take turns to come forward and try different ways of making the object move in all possible ways[speed & directions] ( pushing/ pulling/ picking/ hitting/ lowering/ f lying/ kicking / throwing/ shutting/ flicking/ blowing/ tapping etc.)
3. Two students are asked to make note of the various actions used by their peers

After a list of 15 to 20 actions has  been made, the class is asked to classify each of these actions into “PUSH / PULL ACTIONS”

Students' initiatives:

1. The students perform the situations given

3. Group them as PUSH or PULL

EXPLORE

Sub concept 01: Action of forces and its effects

Activity: The teacher starts the activity with discussion on use of forces in daily life. Following the short discussion, the teacher gives a set of situations to the students and asks them to observe changes in motion/ shape/ direction/ speed in all the situations and record it in the table.

Students' initiatives: The students perform the situations and record the effects of force in changing the state of motion, shape, speed, direction etc. A model of table for recording the effect of force on the state of motion, shape, speed and direction of objects is given. Teacher can add more situations in the table.

After this activity, the teacher poses probing questions to the students such as do these changes happen on their own? What makes all these changes happen? Do forces change all four i.e. shape, speed, direction and motion every time they act upon an object? and so on. The Teacher also asks the students to justify their answers.

Sub concept 02: Magnitude, direction, resultant of forces

Three marbles of different sizes are taken (small, medium and large size). The medium size marble is kept in a small distance away as target marble. The small marble is made to hit the target marble and the distance travelled by the target marble is noted down. Then, the large marble is made to hit the target marble and the distance travelled by the target marble is noted down.

The teacher then asks the students

1. Whether they noticed any difference in the distance travelled by the target marble in the two situations. Why was it different? (Or) why was it not different? What could be the possible reasons for the difference?
2. What is the  difference between  the two marbles? One was  small (with less mass) and  the  other  was  large (had more mass)
3. Why did the marble move  less in first case and farther in the second case?

Because the force that was acting on  the target marble was less in the first case and higher in the second case.

1. What is the relationship between force and mass?

An object with more mass can exert more force compared to an object with less mass. [More the mass – higher the force]

Sub concept 03: Types of Force

Teacher can give the following activities to the students to exploring the contact and non- contact forces. The following table has example activities and teacher can add more activities to it.

Exploring Contact and non-contact forces

EXPLAIN

The students are asked to summarize their learning from the activities as groups/ pairs/ individuals in a sequence. The tables, worksheets, observation & notes taken by children can be used to help them summarize.

The teacher asks the following questions to ensure understanding of the concepts.

1. How do you define force?
2. How did the larger marble move  the target marble for a longer distance compared to the smaller marble?
3. Why can't a humanbeing (70 kg approx.) push and  make a concrete wall move?
4. When two students push the table with same force from opposite directions, the table remains unmoved. How does that happen?
5. A marble moving at a particular speed travels with increased speed when being hit by another marble from behind. Why?
6. How does the amount of force affect the distance travelled ?
7. How do we make the striker in a carom board to hit coins at different distances and different directions?
8. Why does the ball thrown to the sky returns to earth? What kind of force is involved?
9. A ball hit by a bat stops moving after travelling for  some  time. Why  does this happen?
10. How can we differentiate contact forces from non-contact forces?

The teacher can also show a set of videos for enhancing or to bridge the gaps in the understanding of the students, if necessary

1.    What is force? https://www.youtube.com/watch?v=dYreKZYJ xaE

1.    Force, work and energy relationship https://www.youtube.com/watch?v=PD7a1EWjsTc

3.    A force is a push or pull https://www.youtube.com/watch?v=_dcxCdB-s8

5.    What is Friction? https://www.youtube.com/watch?v=C7NPD9W0kro

Scientific Vocabulary: Push, Pull, Force, Speed, Magnitude, Direction, State Of Motion, Resultant(net) Force, Newton, Contact, Non- contact, Magnetic, Gravitational Force, Electrostatic Force, Muscular Force, Frictional Force

ELABORATE

Teacher asks the students to observe a video of a cricket match and identify the different forces and their effects.

* 2009 Ashes_ 1st Test Highlights (HD)- https:// www. youtube. com/ watch? v=N-MvbaqLjpc

1. What are the forces involved when the players stand still on the ground?
2. How does the muscular force of a bowler, batsman  and  a fielder  change the state, speed, direction of the ball?
3. A player hits the ball very high that no fielder near the batsman can even touch the ball. But a fielder at the boundary line catches the ball and gets him out. How is this possible?

In order to make children realize the importance of non-contact and contact forces and how different types of forces are constantly at play in our daily life, the teacher can provide more activities, have discussions and use videos.

Electrostatic Force:

The principle of electrostatics is used for painting a metal surface of a car, in photocopiers (Xerox), chimneys of industries etc. Following activity can be used to for experiencing the electrostatic force. An inflated balloon was pressed against a wall after it has been rubbed with a piece of synthetic cloth. It is observed found that the balloon sticks to the wall. What force might be responsible for the attraction between balloon and the wall?

Magnetic Force:

Magnetic locks in cupboards, bullet train (using levitation)

Video: Mobile Crane Electromagnet JCB Lifting Magnets Lifting Magnet Equipment https://www.youtube.com/watch?v=UW9yfNH MumQ

Model Maglev train https://www.youtube.com/watch?v=8u_7beSyi II

Muscular Force:

Teacher could provide some situations and have discussions around it. Example, a blacksmith hammers a hot piece of iron while making a tool. How does the force due to hammering affect the piece of iron? At the same time a goldsmith uses a different set of tools? What are the reasons for these differences in tools?

What happens in the following activities? Bulls puling a cart, pumping of blood by heart, opening & closing of eyelids, chewing the food particles, speaking, etc.

Frictional Force:

The teacher shows the following video and makes the children make connections to where all friction acts in their daily life.

Video - FrictioninDailyLife https:// www. youtube. com/ watch? v=qy- EJRDyt-A

Other examples: Cycling to school, carrying their bag, brushing the teeth, walking, running, playing,

EVALUATE

Teacher can evaluate the students' understandings through various methods, such as oral, written and projects. Here, we have provided some sample questions for evaluation.