Contrasting student and scientific views

Student everyday experiences

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Many young students will have had actually memorable yet often confound experiences with magnets and also magnetic materials. Magnetic products are frequently encountered about the home, frequently holding tiny objects on the kitchen fridge or keeping cupboards and fridge doors closed. Numerous children’s toys employ weak magnets to ‘stick’ products together (e.g. Wood train carriages) or are offered in an easy children’s building and construction toys to allow them to conveniently assemble more complicated structures without the require for confusing adhesives or difficult connections. Toys really rarely exploit magnetic repulsion.

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Many younger students space yet to form strong views or in numerous cases any views in ~ all around how magnets communicate with issue or each other. They do not see the have to discriminate between magnetic forces and also electrostatic pressures (or gravity). To them, these often appear to be typical experiences that the very same invisible non call force, usually just attraction. For example, a balloon ‘rubbed’ v a towel resulting in that is attraction to an additional object is generally described erroneously by young student (and also some adults) as having been ‘magnetised’ in some way.

Students’ confusion approximately non contact forces is explored in the focus idea Electrostatics – Level 4.

It is well established that enlarge students hold a selection of views around magnetism that vary substantially in their sophistication, varying from magnetic models with neighboring ‘clouds’ of action to ideas around ‘electric rays’ and ‘fields’. However, numerous younger students just associate magnetism v a ‘pulling force’.  Understandably their naive model has actually no predictive or explanatory power and also they generally do no perceive the need to do more than identify and also label the attractive or the less frequent repelling behaviour together magnetic.

Research:  Erikson (1994), Borges & Gilbert (1998), Haupt (2006), valve Hook & Huziak-Clarke (2007), Ashbrook (2005), Hickey & Schibeci (1999), Maloney, O’Kuma, Heieggelke & van Heuvelen (2001)

Scientific view

We generally encounter magnetic areas in our daily experiences (e.g. The earth’s magnetic field and also magnetic fields developed by electrical current). However, the vast majority of the magnetic fields approximately us are merely too weak to cause any type of observed effects or continue to be ‘removed from us’ because they space utilised in more complicated machines like electric motors and computer hard drives.

Magnetic attraction and repulsion is just one of three basic non call forces in nature. The other two forces are electrostatic and also gravitational (see the emphasis idea forces without call at level 4, Electrostatics – Level 4 and Gravity - Level 6).

The vast bulk of magnets us encounter (e.g. Fridge magnets, door catches and also magnetic toys) are made from materials which space ferrom​agnetic. These products are based upon mixtures that iron, nickel or cobalt together these room the just three well-known ferromagnetic elements. Stronger commercial magnets deserve to be made through these and also the addition of much more expensive rare earth elements.

The atom in ferromagnetic products are different due to the fact that they deserve to behave like little magnets. Usually the magnetic field approximately each atom point out in a arbitrarily direction leading to them cancelling each other out (see figure 1). But if the surrounding magnetic ar is strong enough, it is feasible for them come align so they each add to create a more powerful magnetic ar in the material (see figure 2). Lock can additionally remain aligned as soon as the surrounding ar is removed developing a long-term magnet.

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Typical magnets found roughly the residence or offered in etc ‘pick ups’ or fish tank glass cleaners are constructed with ferromagnetic materials and also can create permanent magnetic areas with intensities up to 3000 times that of the earth’s magnetic field.Ferromagnetic products are usually very brittle and also will easily chip or fracture if reduce or permitted to slam together. They will likewise lose their long-term magnetic nature if cook strongly. All of these actions reason the individual atoms to shed their alignment.The magnetic fields surrounding all magnets are stated to have two poles, called North and South. These names originate from the observation that magnets will align in the direction the the earth’s weak magnetic field if enabled to swing freely i.e. Direction recognize magnetic compasses depend on this rule to operate. The ‘north pole’ the a magnet bring away this name due to the fact that it constantly points in the direction of the earth north geographic magnetic pole.Similar magnetic poles repel and unlike magnetic poles lure each other. 

Critical teaching ideas

Magnetic pressures are non call forces; they traction or push on objects without poignant them.Magnets are only attracted come a couple of ‘magnetic’ metals and not every matter.Magnets are attracted to and repel other magnets.

At criter up to and also including Level 3, the is ideal to encourage students to observe and explore magnetic phenomena v play. Students have to be helped to develop basic understandings the the observed attraction that magnets to part ‘special’ metals (not every metals) and also their attraction and also repulsion to other magnets. Students must be encouraged to discriminate in between magnetic forces, electrostatic and gravitational forces as being various to every other but examples of forces that have the right to act there is no physical contact taking place i.e. Examples of non contact forces.

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Explore the relationships between ideas about magnetism and non contact forces in the Concept advance Maps –  Electricity and Magnetism.

Teaching activities

Provide an open problem to be explored via pat or through difficulty solving

Provide students through a range of different materials because that them to inspection which ones have magnetic properties. This materials might include samples of: paper, plastic, polystyrene, wood, glass, rope, leaves, ceramic, rock, and also some objects made of iron or steel. Look to use only metallic objects made from stole or steel so students have the right to see the being created of a solid metallic material is a typical property.

Provide students v a bag that samples (say 12-15) and have them test the samples with a bar magnet or refrigerator magnet to see which ones are attracted come the magnet.  Ask lock to kind the objects into two separate groups: those that appear to be attracted to a magnet and those which perform not.

Invite the students to market suggestions of common features that the objects in the team that were attracted come the magnet. Is it your colour, load or the problem they are made the that may make the difference? have students suggest and test their principles to identify feasible common properties.

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Next, ask student if all objects make of metallic materials are magnetic. Have any students had experiences which suggest otherwise? Now provide students through a number of objects do from different metals and also ask them to kind the objects into two piles, predicting i beg your pardon objects will be attractive to a magnet and which will certainly not. Some instances of metals and their sources might be: aluminium cans or foil, brass keys, copper pond or wire, stole screws or nails, zinc flashing or solder, iron bolts or nails, lead fishing sinkers and also nickel welding rods.  

After sorting the objects students can then test them to see if they have actually correctly suspect which products are magnetic.

The intention below is come encourage students come test various materials and also through examination recognise that just a couple of metals have actually magnetic properties. Critical point to it is in made is the in our daily experience many metals appear to be magnetic due to the fact that the most widely used steel is steel containing iron.

Open up conversation via a mutual experience

Most college student are familiar with magnets ‘attracting’ magnetic materials or gift attracted to some metallic surface such together fridges and also white boards, yet they are far less familiar with magnetic forces that repel each other. This is make more difficult for students come explore due to the fact that they must have actually at least two magnets of comparable strength and many the the acquainted advertising refrigerator magnets provided for straightforward investigations space weak and also constructed in a method that they have no identifiable magnetic poles.

Try to attain a number of ‘fish tank’ glass cleaning magnets i beg your pardon are supplied in bag or ‘cow magnets’ obtainable from some agricultural produce stores. The surface of this magnets space well protected and also will alleviate the risk of students accidentally pinching fingers or the magnets shedding fragments if handled roughly.

Ask the college student to inspection what they have to do to make the magnets attract and also repel every other. Have them identify various ends of every magnet through identifying stickers. Just how well can the students guess what will take place when the magnets are brought near to each other?

Now encourage students to use masking tape to solve one magnet top top the roof that a toy car. Usage the hand held magnet to push the auto along without emotional it or to lure the vehicle towards the by transforming its orientation. Deserve to students suspect if the magnet on the car will be attractive or repelled through the method of a brand-new magnet?

The intention here is for students come recognise that magnets have the right to repel and attract every other. In ~ this level it is not taken into consideration important for students to be able to recall that favor poles repel and also unlike poles attract, however to recognise that magnets can repel and also attract there is no making physical contact and that their orientation is important.

Open conversation via a common experience

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Students deserve to be encouraged to inspection if magnetic forces pass through various other non magnetic materials. To catch student interest, location a magnet (such together a fish tank glass cleaning magnet) ~ above a classroom table. Introduce one more magnet (the various other glass cleaning magnet) under the table for this reason the two space strongly attracted.  Position the magnet therefore you have the right to move the magnet under the table with your knee or other hand. The magnet top top the table optimal will follow the motion of the magnet below. This mysterious movement of the magnet ~ above the table will impress students yet eventually lock will discover the ‘trick’ that the second magnet under the table.

Have the students secure a magnet to a stand or the peak of a small water bottle utilizing some ‘blue tack’ or adhesive tape so it overhangs the side challenge of the bottle. Next have them settle a paper clip to a size of cotton with enough length to with from the table peak to the magnet. Ultimately use some ‘blue tack’ to solve the noodle to the table therefore the record clip is just short of getting to the magnet and appears rely in mid air through a gap between it and the magnet.

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Encourage students to inspection if various products will stop the magnetic force of attraction as soon as they space introduced in between the magnet and the record clip. Shot sheets that paper, glass, tile, aluminium foil, copper and also zinc sheet. Do any of this materials have an result on reduce the magnetic force?

The intention below is because that students to observe the magnetic pressures will continue to be unhindered and can travel through most materials without any type of effect.

Helping student workout few of the ‘scientific’ explanations for themselves

Collect a variety of uncoated cable coat hangers and cut and also straighten lock into brief lengths which variety from 10cm to 20cm long. Distribute a pair of these around to students functioning in bag or triplets, making sure they space given various sized lengths. Additionally pass around a number (5 come 8) of little paperclips to each group. Deliberately execute not pass out any type of magnets simply yet to prevent students bringing castle into contact with the cable lengths.

Encourage the students to investigate if any kind of of the lengths the wire room successful in attracting any kind of of the paperclips. If the cable lengths have actually not made previous call with any kind of magnets then they should display no magnetic properties and not harass the paperclips.

Now pass the end a long-term magnet to every of the college student groups and demonstrate just how you have the right to use one finish of the magnet come stroke the wire size consistently in one direction resulting in it to end up being magnetised. Students deserve to then repeat this v their own lengths that wire and also determine if they have been effective in making a magnet by testing its capacity to tempt or lift up numerous paperclips. 

This an approach of magnetisation is continuous with the idea of utilizing a magnetic ar (from the magnet) to significantly align the direction of the atom acting as tiny magnets in the wire. Share this explanation through students is no recommended.

Have students explain what lock did and discuss how successful they were in make a magnet.

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Collecting evidence and data for analysis

After student have successfully made one size of wire right into a permanent magnet, set them the difficulty of making the most powerful magnet castle can. They have the right to again test your success through attracting and lifting as many of the paperclips as they have the right to with their wire magnets. Have students indigenous each team record the variety of paperclips your magnet deserve to lift. Encourage students to investigate different properties the the wires the may contribute to making better magnets e.g. To compare the variety of times each to be stroked, the size of the wires and the methods used to stroke each wire.