Lesson 1 

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Ja

Lesson Title:  Magnetic Attraction

NC Ref:  Sc4 1d
 

Objectives:    

MK -  magnetism is a non-contact force, iron, steel and iron oxide are magnetic materials, not all metals are magnetic, magnets can attract and repel each other, the ends of a magnet are called the north and south poles, the words: magnet, magnetic material, iron, steel, attract, repel, north pole, south pole, bar magnet
SK -  magnetism does not pass through magnetic materials, cobalt and nickel are magnetic materials, how to make a magnet by stroking, rules for attraction and repulsion. Words: cobalt, nickel
CK -  how to make and destroy magnetism, and a basic explanation of why these methods work. The words: atom, domain

Lesson outline: 

Starter activity:
Show ‘executive toys’ such as floating magnets, magnet marbles and field around a magnet are available, you could use these to initiate discussion of magnetism and its effects. The diagram below shows how to set up the ‘floating paper clip’ demonstration, with a paper clip attached to the bottom of a retort stand using string which could also be used to initiate discussion.

Alternatively, you could carry out a brainstorming or free writing activity, asking pupils to write what they know about magnets and magnetism.

Main course:
There are six activities mentioned in the technicians guide which could be done as circus of experiments.
      -  they could try their own version on the floating paper clip
      -  attraction and repulsion of two magnets
      -  floating ring magnets - demonstrating repulsion
      -  which is the magnet? This is done using the two "magnets" that come with the "lens' law apps.
      -  home made magnet
      -  which are the magnetic materials?
         See info. cards to tell the pupils what to do.

Imaginative groups could be encouraged to design a machine that automatically sorts out the magnetic materials from the non-magnetic.  A possible solution is to slide the object (possible cans) down a slope with the magnet at one side - this is probably best done using the big magnadure magnet.

Pupils will need notes summarising the main objectives

Plenary
Carry out a ‘connectives’ exercise to revise the content of this topic. Connectives are a set of sentences for pupils to complete in their own words, including one of the following words: and, because, but, however, such as, therefore, which, to, so.

A set of statements is provided as Worksheet 8Ja/4 (from the website) for pupils to use, or the worksheet can be projected. Pupils can be given five minutes to complete their sentences, and then they can share their ideas with the class.

The obvious answers to many questions involve using ‘because’ as a connective, but more able pupils should be encouraged to use the other connectives if they can.

Timings:

10 mins

30 mins

20 mins

Homework Suggestion: 
Worksheet 8Ja/2 provides a wordsearch activity that could be used.
Top set would be stretched by worksheet 8Ja/3 - which outlines magnetic domains

Resources:
Magnetism circus - arranged into 2 lots of six sets together with the relevant laminated instructions cards:
1. clamp and stand, bar magnet,  paper clips,  cotton
2  two bar magnet,  clamp and stand, paper stirrup (made by stapling a strip of paper and trapping a length of cotton thread in the staple)
3  floating magnets:  clamp stand with aluminum or wooden rod,  two ring magnets
4  two bar magnets  piece of unmagnetised iron/steel that looks the same as the magnets (use the two magnets from the lenses law demo) (poss. only one set of this apparatus)
5  bar magnet,  pin or straightened paperclip,  paperclips
6  labelled thin sheets of iron, copper, wood, paper, nickel (if possible), aluminum, Perspex, etc.
Drinks or washed out food cans - some of which are magnetic some aren't

Lesson 2   

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Jb

Lesson Title:  Pointing North

NC Ref: 
 

Objectives:    

MK -  a magnet will point north if is can move freely
SK -  magnets have 2 poles, north seeking & south seeking - common to shorten this to "north" and "south" pole.  The north magnetic pole acts like the south pole of a bar magnet
CK -  the difference between true north and magnetic north is the "variation", Pupils could know about William Gilbert and his contribution.

Lesson outline: 

Starter activity:
Show the worksheet 8Jb/4 (from the website - scroll down), and ask them to produce questions to fit the answers given. Pupils can work in small groups before holding a short class discussion to decide what the questions should be. This can be done orally.

Main course:
It is useful to discuss methods of navigation before showing a compass.  You could show Wksht 8Jb/2 to determine whether pigeons use magnetism.

It might be useful to show Wksht 8Jc/3 to discuss true and magnetic north.  It might be possible to borrow some orienteering maps off geography - in order to spot the difference.  NB OS maps also show true and magnetic north - but they also introduce Grid North which might be a bit much to explain.

Practical - making a homemade compass - ask the pupils to devise a method of suspending a magnet so it can point North.  Pupils could decide if they wish to use the magnet or make a smaller lighter magnet using a needle.  They might float the needle or suspend it from a thread.  This could be done in the form of a competition.

Plenary:
Worksheet 8Jb/5 (from the website - scroll down) can be shown to help pupils revise the work from the first two lessons of this Unit. The worksheet provides a set of statements which pupils are asked to rank as true or false, and to correct any false statements. They should then decide whether the second statement of each pair explains the first – they should use their corrected versions for this part of the activity.

Timings:

10mins




5mins


5mins


30mins

10mins



 

Homework Suggestion: 
The plenary could be done as a homework - since this worksheet is available on the web.

Practical:  Homemade compass: class set of: bar magnets,  pins,   cork or wood, washing up  bowl,  cotton thread,  clamp and stand,   paper,  Blu-Tak or Plasticine,  stapler, mop and bucket for water spills, OS or orienteering maps - borrow from Geography, compasses

Lesson 3   

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Jc

Lesson Title:  Force Field

NC Ref: 
 

Objectives:    

MK -  a magnetic field is the space around a magnet, where is has an effect, and it can be viewed using iron filings.  The shape of the field around a bar magnet, and that the earth has a magnetic field
SK -  how to use a compass to plot the shape of a magnetic field, the direction of the field is from north to south; the earth magnetic north is not exactly at the north pole
CK -  the dip of the earth magnetic field; the causes of compass deviations

Lesson outline:

Starter
Worksheet 8Jc/6 (from the website - scroll down) provides a word puzzle that will help pupils to consolidate the work of the previous two topics.  Answers:  1   same  2   cobalt  3   magnetic  4   nickel  5   repel  6   attract  7   iron  8   south  9   compass

Main course:
Pupils should already know that magnetism is an non-contact force.  Discuss how close does a magnet have to be before the magnet affects it. 

Video clip: Science in Action - magnetism and electromagnetism - Howie investigates how a magnet can be used to help climb up the hull of a ship.

Introduce the idea of a magnetic field - just as a in a field of grass - a magnetic field is a place where we find magnetism.  Pupils can visualise the shape of the field using a bar magnet, covered in paper, sprinkled over with iron filings.  This activity is much cleaner if the magnets are wrapped in cling film before use.

More able groups might be able to use a compass to plot the field around a magnet, see worksheet 8Jc/1and to move the compass above and below the magnet to prove that the field is in 3d.

Pupils could look at a diagram of the field around the Earth - from P. 121 of the text and answer questions 2-5

Teacher demo: demo the direction of the magnetic field:  Use a magnetised pin or needle - stick it vertically through a cork so that it floats with it's north pole uppermost.  If a bar magnet is held just above the surface of the bowl of water and the needle put in the water near the north pole of the magnet, it should follow a curved path around to the south pole.

The dept has a demo showing the 3d shape around a bar magnet using iron filings in oil - the demo on Video clip: Science in Action - magnetism and electromagnetism is also good.

Plenary
Ask pupils to summarise the contents of this Unit so far by drawing a concept map. More able pupils should be able to draw their own maps, but Worksheet 8Jc/7 (from the website - scroll down) could be used to help less able pupils.

Timings:

10mins

40mins

10mins

Homework Suggestion: 
MK: Worksheet  8Jc/3
SK:  Worksheet  8Jc/4
CK:  Worksheet  8Jc/5

Resources: 
Apparatus per group:  two books,  bar magnet covered in cling film,  sheet of paper,  iron filings in shaker,  eye protection,  plotting compass
Demo:  magnetised pin stuck vertically through a cork,  bar magnet,  bowl of water

Lesson 4   

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Jd

Lesson Title:  Sounds magnetic

NC Ref: 
 

Objectives:    

MK -  electricity causes magnetism; that an electromagnet is a coil of wire; one way of increasing the strength (e.g. higher current, more coils, soft iron core);
SK -  three ways of changing the strength of an electromagnet; how a make and break switch switch works
CK - 

Lesson outline: 

Starter activity:
Show pupils that a bar magnet can pick up a steel can or other object, and discus how this could be useful in a scrap yard. Discuss how the scrap could be put down again – pupils should realise that a bar magnet is not practical in these circumstances. You could then demonstrate an electromagnet, and ask pupils to suggest ways of changing its strength – this part of the activity will lead naturally into Practical..

Main course:
Pupils investigate ways of changing the strength of an electromagnet.  This is a possible Sc1 opportunity in which the following variables could be investigated or controlled: number of coils, voltage, type of core.  See worksheets: 8Jd/1 or 8Jd/2

Plenary:
As this is likely to be a long activity - pupils would benefit from just a quick summary of the main objectives

Timings:
 

10mins

45mins



5mins

Homework Suggestion: 
Pupils could write up their conclusions and evaluations

Resources: Sc1 planning laminates + pens,  class set of: insulated wire,  connecting wires,  power packs, crocodile clips,  paper clips,  soft iron nails,  glass rod,  wooden rod or pencil
 

Lesson 5   

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Jd/2

Lesson Title:  Relays and circuit breakers

NC Ref: 
 

Objectives:    

MK - electromagnets are used in bells; relay is a switch that is opened and closed without being touched; relays are used for safety
SK -  how to use a relay to control a bulb; why a relays is used in a car starter motor
CK -  circuit breakers can be used instead of fuses; RCDs are a safer alternative to circuit breakers and fuses

Lesson outline: 

Starter activity:
Show an electric bells - and dismember is to show how it is working. 

Link to s-cool.co.uk ... for bell / relay diagrams. 8Jd/6 is a worksheet showing its operation with some questions.

Main course:
Demonstrate the action of a reed switch using a magnet to switch it on.  If the class is quiet enough they can hear the click as the two reeds make contact.  If the pupils wish to have a go - it could be combined with the practical below:

Practical: pupils build a reed relay circuit to see for themselves how how electricity can be used to switch a separate circuit on and off.  See:  8Jd/4

Brightest buttons only: pupils could build circuits using changeover relays - see Wksht 8Jd/4 for the challenges and 8Jd/5 for hints and help for the pupils.

Plenary:
Worksheet 8Jd/9 (from the website) (scroll it down) provides material for a ‘spot the mistake’ exercise. The worksheet provides pictures of a bar magnet with its magnetic field and a starter motor circuit which can be projected.

Timings:

10mins






40mins


 

10 mins

Homework Suggestion: 
Many devices use electromagnets - pupils could be encouraged to research and report on a particular device.

Resources: 

      electric bells with removable cover,  power packs,  connecting wires,   reed switches,  cells,  bulbs,  bar magnets,  switches, crocodile clips,  changeover reed switches, card,  scissors, sticky tape, buzzer, piece of wood or polystyrene, beaker,  motors

Lesson 6

Unit Title:  Magnets and electromagnets
Caretaker:  IL

Unit No   
8Je

Lesson Title:  Coils and cores

NC Ref: 
 

Objectives:    

MK -  the shape of an e/m field is similar to that from a bar magnet
SK -  e/m strength is increased by use of a core made from a magnetic material; electromagnets are used to record sound onto cassette tapes and computer hard drives
CK -  the shape of the field around a current-carrying wire is circular; that the direction of the field of an e/m depends upon the direction of the current; how magnetic recordings are made and played back; how to magnetise and demagnetise iron using dc and ac currents + a basic explanation of why these methods work.

Lesson outline: 

Starter activity:
 

Use the CAP suggestions on the Thinking Skills page for this Unit to revise work covered in the Unit so far (see the notes on CAP activities on page 10 of Teacher's Guide 7). Allow pupils five minutes to note down their ideas before reporting back to the rest of the class. These CAP suggestions, and some additional ones, are reproduced below:

8Ja – Two pieces of metal are attracting each other.
8Jc – A compass needle does not point north.
8Jd – An electromagnet will not pick up a can of food.
8Jd – An electric bell will not work.
8Jd – A car engine will not start.

Main course:
Demonstrate the similarity between the shape of the field around a bar magnet and electromagnet - probably best done on a sheet of Perspex on an OHP.  Sprinkle iron filings.  Ask the pupils to predict if there would still be a magnetic field without the iron core - show that there is but point out the core makes the field stronger.

Pupils could be asked to predict how the shape of the field would change if the strength of the electromagnet was increased.

This leads to a ...
Practical: in which pupils determine the shape of a magnetic field around a wire pushed vertically through thick card using plotting compasses.  The pupils could predict and then test what happens to the direction of the field if the connections to the pply are swapped over.

Alternatively Worksheets 8Je2 and 8Je3 cover similar ideas - and Wkshts: 8Je4     8Je5  look into recorded music  8Je6   considers demagnetisation.

Plenary:
Worksheet 8Je7 (from the website) (scroll it down) provides a set of cards for a question loop activity that can be used to summarise the whole Unit, and act as a starting point for revision.

There are 30 cards provided. All cards must be used to close the ‘loop’ – if you do not have 30 pupils in the class, give some pupils more than one card. Alternatively, copy two sets of cards so that each pupil has at least two cards – two hands should then go up in answer to every question, and pupils are less likely to mentally switch off when they have used their card.

Timings:

15mins



















35mins


 

10 mins

Homework Suggestion: 
Revise for a test - or do the quick quiz as a semi-test - see dept guidelines on end of modules

Resources: 
Demo:  coil of insulated wire,  iron core (nail or iron rod),  connecting wires,  crocodile clips,  power pack,  sheet of perspex,  iron filings,  eye protection, overhead projector and screen

Apparatus per group: coil of insulated wire, iron core (nail or soft iron rod), connecting wires, crocodile clips,  power pack, sheet of perspex,  plotting compass,  clamp stand,  fairly rigid card

Risk Assessment:
Eye protection required for use with iron filings, careful with low voltage using the power packs as the wires can become very hot.