PR-0552UK Primary Science - Book 2

The torch experiment
Light ~ Activity 4
Objective
• investigate the relationship
between light and materials
Working scientifically
• Questioning
• Observing
• Predicting
• Investigating and experimenting
• Analysing (sorting and
classifying)
• Recording and communicating
Designing and making
• Exploring
• Making
Background information
If light that hits a material travels
straight through it then the material
is transparent. Objects can be clearly
seen through transparent materials.
If no light passes through an object
then it is opaque and nothing can be
seen through the object.
If a little light is transmitted through
a material and close objects cannot
be seen clearly then the object is
translucent.
Before the lesson
Materials needed
• Variety of materials with opaque, transparent and translucent qualities (e.g.
plastic bottles, cellophane, thin nylon, cotton wool, tracing paper, pencil, scissors,
water, frosted glass, thick coloured plastic), strong torches or an OHP, three
cardboard boxes.
Preparation
• Label the three boxes ‘Allows Light to Pass Through – Transparent’, ‘Prevents
Light Passing Through – Opaque’ and ’Allows a Little Light to Pass Through –
Translucent’.
• Divide the class into small groups. Provide a variety of materials for the pupils
to test in their groups.
The lesson
Stimulus
• Demonstrate to the pupils what they will be doing in the torch experiment.
Shine a torch through each type of material. Introduce the terms ‘transparent’,
‘opaque’ and ‘translucent’. Discuss their meanings.
What to do
• In groups, test each object or material by holding it in front of the light.
Categorise them into groups according to how much light passes through.
• Discuss the types of shadows they form.
• Revise the terms ‘opaque’, ‘transparent’ and ‘translucent’. Show the pupils the
boxes and get each group to place their materials in the correct box.
• On the worksheet, pupils use their own words to explain each term and make
a list of objects under each of the headings.
After the lesson
Answers
1. Opaque – doesn’t allow light to pass through.
Transparent – allows all light to pass through.
Translucent – allows some light to pass through.
2. Teacher check
3. Answers will vary but may include such things as:
(a) blinds, clothing, walls, doors
(b) windows, glasses, clear plastic, packaging
(c) frosted glass, coloured glass
Viewing Sample
Additional activities
• Design and cut out scary shapes from opaque and translucent materials and
attach to sticks. Get the pupils to try holding the shape close to a strong light
and then further away. What do they notice about the shadow?
• Perform puppet plays with the shapes.
Display ideas
• Display the shapes made in ‘Additional activities’.
• Display materials on a table under the headings of ‘opaque’, ‘transparent’ and
‘translucent’.
44 PRIMARY SCIENCE ~ Prim-Ed Publishing ~ www.prim-ed.com