Can the year 7s do it?

Linking balanced and unbalanced forces to motion

Alan Wallis teachingtoinfinity.wordpress.com

ContextA middle set mixed gender year 7 classMIDYIS predictions between NC levels 5 and 660% receive learning support (mostly dyslexia, some dyspraxia and dyscalculia) Prior Learning:• Open-ended personal whiteboard notes on

forces• How to draw a force diagram (forces from centre,

length of arrow proportional to size of force)• Experience of springs, rubber ducks on water etc.

What I wanted them to achieve

• When an object is stationary when the forces on it are balanced

• When forces are balanced objects move at a steady speed or remain stationary

• An overall (unbalanced force) produces a change in speed

Order of play

AssessmentPlan

OutcomeAssessment

Worksheet ‘Your Ideas on Forces’

1. Draw and label the forces acting on this forward-moving car;

2. Draw the forces acting on this book;

4. Albert is sledging down a hill on to a level field. Discuss this situation in terms of forces.

5. A ball is thrown up in to the air. It leaves the person’s hand, goes up through point A, gets as high as B and then comes back down through A.

Think of some questions that you would like to know the answer to about forces and movement.

Now think about how you could find out the answers to these questions for yourself.

The Plan• Make the students realise that upthrust only comes

from water and that a solid surface provides a reaction force.

• Use length of arrows to show size of forces.• Become confident using the terms balanced and

unbalanced forces.• Link unbalanced forces to acceleration• Link balanced forces to steady speed• Understand that there doesn’t have to be a force on

something for it to be moving• Link unbalanced forces to deceleration

To start with…

1. What is the force that stops you falling through your chair or whatever you are standing on?2. Why do objects full of air float?3. How do some objects (planes, birds, clouds) fly?4. What are the forces on a fighter jet?5. What other forces are there?6. How many kinds of forces are there and what are their names?

The Falling Man

AcceleratingDeceleratingSteady Speed

StationaryBalanced

Unbalanced

Student C

The Rolling Ball

The behaviour of a rolling ball if there was no friction.

The Car on a Slope

Exactly the same as the sledge question.

Design an experiment to find out which ball experiences the most friction.

Things to think about;1. What are you going to change in the

experiment?2. What are you going to measure?3. What things will you need to keep the same?

How will you do this?4. Discuss the forces acting on the ball at

different stages

Design an accelerometer to help show astronauts when their spacecraft is accelerating.

Things to think about;1. When you are in a car how can you tell it’s

accelerating?2. How could you show this with a device?3. Is there a way to show the amount of

acceleration?

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