Melting and Freezing
These downloadable videos and animations are part of the multimedia package Stuff and Substance, developed by the Gatsby Science Enhancement Programme (SEP). They can be used to develop the idea of a substance as a kind of ‘stuff’ which has a definite melting point.
The idea of a melting point can be introduced using pure samples of substances as the temperature that is ‘just hot enough’ to start melting. In terms of behaviour, a precise melting point is recognised by a sharp change from solid to liquid. Many students think the melting temperature depends on the sample size – the bigger the lumps the higher the temperature. Although most students see solidifying on cooling as the reverse of melting, many think that this only happens at temperatures well below the melting temperature. The videos show the melting behaviours of substances with different melting points (wax, lead and common salt) and the animations address the temperature aspects of melting and solidifying.
These video and animation files form part of the resources in the section Melting and Freezing in the Stuff and Substance multimedia package, which provides a series of interactive pages that can be used by teachers or students in the classroom.