The Teaching and Learning of Mass and Weight.

There are some problems encountered by pupils in learning of mass and weight in both secondary and primary schools.
According to the ordinary person in the community ,mass and weight are identical. But actually mass and weight are not the same.However, there are ways of dealing with mass and weight that can help pupils to understand the concepts more clearly.The problems in mathematics and sciences for both pupils and teachers is mainly caused by initially telling learners that mass and weight are the same.
Mass is the amount of matter a body has and is related to number of atoms in that body. Mass is measured in milligrams,grammes ,kilogrammes and tonnes.
Weight is the force exerted by a body via gravity. It is measured in Newtons.
(weight =mass multipled by gravity)
Bare in mind that at times we may be weightless but not massless!
Pupils should be aware that weight changes ,but mass remain constant ,for example an object in hand you feel weight but not its mass.
We may use balance or spring scale to measure weight. The gravity pulls the body downwards .
But the major problems is that most of these weighing instruments are calibrated in mass units.Hence many people frequently say ,'I weigh 70 kgs' Remember we said weight is measured in Newtons . Will this be what the street persons say?So what are we teaching these people.
One of the best ways to clarify this controversy is to use mass balance in schools . Teachers can collect wooden coat hanger ,fishing line or string and two wide shallow ,plastic containers.
All materials are usually readily available and the construction is simple. A counter-balance of plasticine (stiki-stuff) may be needed.
Children compare masses using the balance ,since gravity acts on both pans ,we are not measuring forces but comparing masses of the objects. Even if you use a so-called weight ,for example 10 kg ,this is really a mass so pupils can compare two objects.
Children should used to make statements like:
'This object has the same mass as one of the 20kg'
'The brick weighs the same as a mass of 2kg (ie .the brick has a mass of 2kg)
In this way the children are demostrated the equivalence.
Moreover the children may use three or more objects to compare .The teacher can direct them to write statements of transitivity. (order) .For example Lee is greater than Tom and Tom is greater that Madelene. Lee must be greater than Madelene.
Weight and mass have always been difficult to teach clearly . The effort to distinguish between the two at an elementary stage worth making for the sake of children in future.