The focus on a specific example of a solid, together with the visual resources of
‘attitude’ (horizontal and vertical angle), Contextualisation, illumination, perspective,
and proportion, combine to realise an orientation to knowledge that draws on both the
realism of ScientificZtechnical orientation and naturalistic realism. In short the CD-
ROM draws on the realism of the student’s everyday world at the same time as
inducting them into the perspective of science. The tension between the perspective
of the ‘frame’ and the central screen is a ‘place’ where the ambiguities of students’
learning can reside.
As the student selects a unit of temperature the image displayed in the ‘screen within
the screen’ is changed to correspond with a representation of the effect of that degree
of heating on the ice-cube. In the ‘Hide Particles’ viewing option a change in the state
of matter is realised visually through the three semiotic resources of shape, texture
and colour. The change in state from a solid to a liquid is represented via a change in
shape from a cube, to a mound, to a flat surface that takes the shape of the container.
The change in state of matter is represented in the change of texture from ‘rough’ to
‘smooth’. It is realised in a change of the hue and saturation of colour, from a pale
blue-white to a darker blue.
While the ‘Hide Particles’ viewing option offers a specific example of each state of
matter, the written labels (highlighted on the keys in the upper-right side of the
screen) remain at the generalised level of ‘solid’, ‘liquid’ and ‘gas’. In other words
the visual resources of the ‘screen within the screen’ (including the modes of image,
colour, and movement) present an everyday view of 'particles' while the written
resources of the ‘frame’ provide a generalised scientific one. This generalised
theoretical view of ‘states of matter’ is realised visually (through image, colour and
movement) when the ‘View Particles’ button is selected.
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