Primary Science Guidelines

"Children in third and fourth classes may identify a third set of materials: translucent materials, such as frosted glass and waxed paper, which allow light to pass through but only in a blurred way. Once the children understand how materials can be classified as transparent, translucent and opaque they should explore the school and its environs for samples of each type. This strand unit provides many opportunities for designing and making with materials that are transparent, opaque and translucent. The exemplars in the science curriculum (pp. 31 & 46) provide children with contexts within which the properties of materials used for making common objects such as lampshades, sunshades and glasshouses are examined. Children can discuss how to test the properties of each material. They might consider that the material used for glasshouses should be both transparent and waterproof. They might test different transparent materials to establish which one does not scratch easily. Such a material may be used to make a pair of sun shades. Samples of lampshades from children’s homes may be examined and their properties assessed. The children can then design their own lampshade, using their own criteria and materials. Investigating colours in sunlight— middle and senior classes.

By the end of fourth class children should know that white light can be split into a range of colours, known as a spectrum. The children can use a slide projector and prism to cast a large spectrum on a wall. They can identify the colours and the order in which they appear on white paper or the screen. Other ways for children to see the spectrum are:

• to place a plastic ruler in the sunlight and watch the spectrum as it appears on the ceiling or wall

• to blow bubbles

• to place a mirror in a shallow container of water in sunlight.

The rays of sunlight fall on drops of rain, which act in a similar way as the prism to form a rainbow. Children can experiment to make a rainbow. Mixing coloured light The children should try mixing the primary colours of light. Three torches should be covered with red, blue and green filters and shone onto a white screen or piece of paper. The children will observe that different colour combinations occur. Green and blue light will combine to make cyan (bluegreen); blue and red light make magenta (purple-red); and green and red light make yellow. Together the red, blue and green light beams should give white light, but only if the colours are pure and are projected at the same intensity. The process of mixing the primary colours of paint is different from mixing the primary colours of light; colour paints have a different set of primary colours. Children should investigate what happens when they look at flowers, crayons and other coloured objects through different-coloured filters, and should record the results.”

Source:

Primary School Curriculum Teacher Guidelines: Approaches to learning about light http://www.curriculumonline.ie/