Year 8 Magnets Heating and Cooling
Teacher Notes
Electromagnetic Pickup
Taken from Nelson Thornes Science Web Enquiry Pack 2
Introduction
An electromagnet is similar to an ordinary magnet except it has the
advantages that it can be switched on and off and its strength can be
changed.
Adam and Amy were investigating the things that affect the strength of an
electromagnet in their science lesson. They built an electromagnet by
wrapping 10 turns of wire around a long iron nail and connecting the ends of
wire to a cell. They decided to test the strength of the electromagnet by
seeing how many iron nails it would pick up. However, the electromagnet
failed to pick up any nails. Adam and Amy decided to add more coils of wire,
but still the electromagnet didn’t pick up any nails. Amy put her hand up and
exclaimed ‘Our electromagnet isn’t working Sir’. She had not noticed that
the electromagnet had picked up iron fillings that were spilt on the bench
from the previous experiment.
The Investigation
This pattern seeking enquiry provides an opportunity for pupils to plan and
carry out a whole investigation. Before the planning stage pupils are asked to
discuss why the electromagnet described in the introduction appeared not to
work. Elicit their ideas and use this discussion to raise the issues of the
need to collect data which is accurate and meaningful. They need to consider
how to get accurate data to allow reliable comparisons to be made between
different factors influencing the strength of an electromagnet.
Encourage them to carry out a preliminary test with a range of materials
(e.g. different sized nails, pins, paper clips) to determine which will give the
most sensitive readings.
The most obvious factors that pupils might plan to change might include
number of coils and size of current. Support may be needed in the latter
case in ensuring the plan is viable. Different groups should be encouraged to
investigate different variables.
When evaluating their results pupils should be encouraged to give reasons as
to why data may or may not fit a pattern. They need to understand that
reliable results lie on or close to the best fit line/curve. Some pupils might
identify the need to take repeated measurements and use averages to
improve reliability. Help them to realise that repeating the experiment may
not give accurate readings because the nail remains magnetised to some
extent once the current is switched off. Elicit ideas about how they could
get around this problem.
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Year 8 Magnets Heating and Cooling
Teacher Notes
Risk Assessment
Warn students that the electromagnet may get hot
Switch of current between readings
Using electricity pupils should be aware of dangers
Suggested Time Scale
Lesson 1
Lesson 2
Lesson 3
Planning
Planning / Carry out
Carry out / Analysis
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Year 8 Magnets Heating and Cooling
Teacher Notes
Lesson 1 Planning
Objectives
To be able to:
 Plan an investigation insuring it is a fair test
 Consider factors which might be relevant
Resources
 Science Web enquiry pack 2 sheet 4.3 pupils notes
 Writing Skills – Using Fewer Words in Reports
 Pearson SC1 Skills for KS3 8J Starter question 2
 Power packs
 Iron nails
 Paper clips various sizes
 Insulated wire
Suggested Teaching Sequence
Starter
Go over introduction with pupils. Demonstrate to them how an electromagnet
works.
Pupils to discuss in pairs why Adam and Amy’s electromagnet did not work.
Brainstorm ways to increase the strength of the electromagnet.
Main Activity
Pupils are then to plan an investigation based on the idea of how to increase
the strength of an electromagnet.
Some pupils may require a writing frame for this.
Need to include: what investigating, prediction with explanation, method,
fair test and design a results table.
To help them with a plan give pupils Writing Skills – Using Fewer Words in
Reports sheet, only do question 1.
Plenary
Pearson SC1 Skills for KS3 8J starter question 2 only
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Year 8 Magnets Heating and Cooling
Lesson 2
Teacher Notes
Observing and Recording Results
Objectives
To be able to:
 Plan an investigation insuring it is a fair test
 Consider factors which might be relevant
Resources
 Science Web enquiry pack 2 sheet 4.3 pupils notes
 SATs 2005 3-6 Q15 Paper 1
 Power packs
 Iron nails
 Paper clips various sizes
 Insulated wire
Suggested Teaching Sequence
Starter
Test base question from SATs 2005 3-6 Q15 Paper 1
Go over answers with pupils discussing why smaller paper clips improve the
precision of results.
Main Activity
Pupils to finish plan started previous lesson
When finished teacher to check plan and results table
Pupils to carry out experiment
Plenary
Teacher to decide could be discussion on what pupils have found out so far
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Year 8 Magnets Heating and Cooling
Lesson 3
Teacher Notes
Presentation and Reliability
Objectives
To be able to:
 Understand reasons for repeating observations
 Consider how methods of investigation can be improved
Resources
 Science Web enquiry pack 2 sheet 4.3 pupils notes
 Pearson SC1 Skills for KS3 8J Starter question 3
 Power packs
 Iron nails
 Paper clips various sizes
 Insulated wire
 Graph Paper
Suggested Teaching Sequence
Starter
Pearson SC1 Skills for KS3 8J Starter question 3 only
Main Activity
Pupils to finish collecting data
Draw a graph of results
Describe pattern from graph if there is one
Write a conclusion explaining what investigation has shown
Plenary
In pairs write ways in which could have altered investigation to make results
more reliable
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