Teacher background information
Year 5 Science Content Description
Physical sciencesLight from a source forms shadows and can be absorbed, reflected and refracted (ACSSU080 - Scootle )
This elaboration provides students with the opportunity to learn about Aboriginal and Torres Strait Islander Peoples’ knowledge and understanding of how light behaves in contact with different materials. The refraction, reflection and absorption of light as it passes from one substance into another is a phenomenon that Aboriginal and Torres Strait Islander Peoples have long observed. This is evidenced in the various ways that Aboriginal and Torres Strait Islander Peoples counter and utilise light. Such knowledge is critical to accurately spear fish in water and to construct housing that provides optimal protection in the environment. This elaboration provides students with the opportunity to learn about the properties of light and how such knowledge has informed Aboriginal and Torres Strait Islander Peoples’ technologies and practices.
Aboriginal and Torres Strait Islander Peoples have a long and ongoing understanding of the properties of light and how light behaves when it contacts or passes through different materials. When light strikes a surface, the rays may be absorbed and converted to heat energy, reflected into the atmosphere or refracted modifying the optical perception of objects. The optical properties of light are well understood by Aboriginal and Torres Strait Islander Peoples, and have informed the development of many successful practices and technologies for millennia.
Ochre is a mineral that has long been a valuable commodity for Aboriginal Peoples and is used as a pigment for decorative and artistic purposes. The types of ochre that can be mined from different sites across Australia vary in type, quality and colour, and some rare ochres are widely sought after and traded over vast distances. Among the most highly prized ochres are those that have a silvery sheen caused by the admixture of other minerals such as cinnabar (mercury sulfide) or fragments of mica, a silicate mineral. These components have high refractive indexes when compared with air, contributing to a shimmering effect when light passes through the air to ochre.
Cinnabar has the highest refractive index of any known mineral. The Adnyamathanha Peoples of the Flinders Ranges region in South Australia quarried the Parachilna mine for the red ochre deposits that contain such mercury compounds. This ochre was highly prized and Aboriginal Peoples, such as the Dieri Peoples who occupied the lands over 500 kilometres north west of Parachilna, and the Mitakoodi Peoples from the Cloncurry region in Queensland more than 1300 kilometres away, travelled to barter and trade ochre with the Adnyamathanha Peoples. The Wilgie Mia ochre deposits on Wajarri Yamatji Country in Western Australia contain a high mica component, giving the deep red ochre a silvery sheen. This ochre was a widely sought-after ochre of significant value prior to colonisation and remains so today. Aboriginal Peoples utilised the firelight refraction from these precious ochres to create a shimmer effect. Such ochres have long been used, and continue to be used today, as body decoration by Australia’s First Peoples. Mica flakes are an important ingredient in contemporary cosmetic products globally. The tiny particles refract light and cause the popular shimmering effect. The use of mica for cosmetic purposes can be traced back many millennia in Australia.
Aboriginal and Torres Strait Islander Peoples use the understanding of the refraction of light in the practice of spear fishing. Spear fishing is a hunting practice that has been undertaken for many thousands of years by many Aboriginal and Torres Strait Islander Peoples. On Mer Island in the Torres Strait, the Meriam Peoples catch fish by spear fishing in both shallow waters while walking along the shore, and in deeper waters from a boat. The Wardandi Peoples of the Noongar nation in south west Western Australia spear fish in traps set to utilise the changing tide. Prior to colonisation, bark canoes were used for spear fishing along the Murray River at night, and firelight from an elevated scaffold in the centre of the vessel was used to provide light and to attract the fish.
Accurate and successful spear fishing requires an understanding of the behaviour of light as it passes from air into water. Refraction is a phenomenon in which the speed of light slows as it passes into a material of higher optical density, resulting in a change of direction of the path of light. Due to this refraction of light, an object in the water appears higher than its actual position. Consequently, to successfully spear an object, the aim of the spear needs to be adjusted to target a lower position. The degree to which light refracts when it passes from air into water depends on whether it is salt or fresh water and the depth of the water. The deeper the water, the greater the effect of refraction. Therefore, in deep water, a greater adjustment is needed to counter the effects of refraction, and a hunter needs to aim well below its apparent position to successfully spear the fish. These differences are well understood by Aboriginal and Torres Strait Islander Peoples and such knowledge has been used for millennia, and continues to be used, to accurately and successfully hunt fish using spears.
Aboriginal and Torres Strait Islander Peoples’ knowledge of the properties of light facilitated the construction of shelters prior to colonisation across a range of geographical locations and in varying climatic conditions. Depending on the environment, homes were constructed to provide shade and protection from the heat or to absorb heat to provide insulation against the cold. When light strikes a surface, the rays may be absorbed, reflected or refracted. If the light strikes a light-coloured surface most of the light is reflected, while dark surfaces absorb light which is then converted to heat. Aboriginal and Torres Strait Islander Peoples understand which natural materials absorb or reflect light in the selection of suitable resources to construct shelters to meet their needs. The Warlpiri Peoples of the Tanami Desert north west of Alice Springs construct shade structures known in Warlpiri language as malurnpa. These shelters consist of a wall that is orientated to maximise shade from the sun and remains open on all other sides to allow air flow. These shade walls are constructed using Spinifex spp. or Eucalyptus spp. leaves due to their light silvery colour that maximises the reflection of light, ensuring the shelter provides the best possible protection from the intensity of the sun. Prior to colonisation, the Jardwadjali Peoples in eastern Victoria constructed large circular huts that were entirely coated with clay to protect against the cool climate; the clay served a dual purpose as it absorbed sunlight for warmth and provided insulation to retain warm internal air.
This elaboration provides students with the opportunity to understand Aboriginal and Torres Strait Islander Peoples’ knowledge of the optical properties of light and examples of the technologies and practices that are informed through this knowledge. The application of this knowledge in different technologies and practices demonstrates Aboriginal and Torres Strait Islander Peoples’ understanding of refraction, reflection and absorption. Students will have the opportunity to learn how the historical practices utilising this knowledge in different technologies and practices continue to be of importance in Aboriginal and Torres Strait Islander Peoples’ lives in contemporary Australia.
In the construction of this teacher background information, a list of consulted works has been generated. The consulted works are provided as evidence of the research undertaken to inform the development of the teacher background information. To access this information, please read and acknowledge the following important information:
Please note that some of the sources listed in the consulted works may contain material that is considered culturally offensive or inappropriate. The consulted works are not provided or recommended as classroom resources.
I have read and confirm my awareness that the consulted works may contain offensive material and are not provided or recommended by ACARA as classroom resources.
The following sources were consulted in the construction of this teacher background information. They are provided as evidence of the research undertaken to inform the development of the teacher background information. It is important that educators recognise that despite written records being incredibly useful, they can also be problematic as they are often based on non-Indigenous interpretations of observations and records of First Nations Peoples’ behaviours, actions, comments and traditions. Such interpretations privilege western paradigms of non-First Nations authors and include, at times, attitudes and language of the past. These sources often lack the viewpoints of the people they discuss and can contain ideas based on outdated scientific theories. Furthermore, although the sources are in the public domain, they may contain cultural breaches and cause offence to the Peoples concerned. With careful selection, evaluation and community consultation, the consulted works may provide teachers with further support and reference materials that could be culturally audited, refined and adapted to construct culturally appropriate teaching and learning materials. The ability to select and evaluate appropriate resources is an essential cultural capability skill for educators.
Alaska Native Knowledge Network. (2011). Spearing fish and the refraction of light. Retrieved from http://www.ankn.uaf.edu/publications/alaska_science/Spear.html
Batty, P. (n.d.). Aboriginal use of rocks and minerals. Retrieved from https://museumsvictoria.com.au/website/melbournemuseum/discoverycentre/dynamic-earth/videos/aboriginal-use-of-rocks-and-minerals/index.html
Cahir, F. (2018). Shelter: Housing. In F. Cahir, I. D. Clark, & P. A. Clarke (Eds.), Aboriginal biocultural knowledge in south-eastern Australia: Perspectives of early colonists. Clayton South, Victoria: CSIRO Publishing.
Dulux. (2019). Colours: Mio. Retrieved from https://www.duluxprotectivecoatings.com.au/colours/mio/
Gaynor, A., Kendrick A. & Westera, M. (2008). An oral history of fishing and diving in the Capes region of south-west western Australia (Report to the south west catchments Council). Retrieved from https://www.web.uwa.edu.au/__data/assets/pdf_file/0011/199865/Oral_history_of_the_Capes_region.pdf
Haddon, A. C. (1912). Reports of the Cambridge anthropological expedition to Torres Straits: Vol. IV. Arts and crafts. Cambridge: Cambridge University Press.
Jones, O., & Selinger, B. (2018). The chemistry of cosmetics. Retrieved from https://www.science.org.au/curious/people-medicine/chemistry-cosmetics
Kerr, C. (2017). Discover Australia’s remote ochre sites. Retrieved form https://www.turu.com.au/articles/Discover-Australias-remote-ochre-sites-04579
Keys, C. (2014). Skin fabric iron shade. Proceedings of the Society of Architectural Historians, Australia and New Zealand, 31, 133-143.
Little J. & Cuz, B. (2019). Where’s Aaron: Year 2: Science: Explain. Retrieved from https://www.littlejandbigcuz.com.au/activity/wheres-aaron-year-2-science-explain
Memmott, P. (2007). Gunyah, Goondie and Wurley: The Aboriginal architecture of Australia. St Lucia, Queensland: University of Queensland Press.
Mining Link. (2019). Mica. Retrieved from http://mininglink.com.au/natural-resource/mica
Museums Victoria Collections. (n.d.). Mineral sample, Adnyamathanha, Parachilna, Spencer, South Australia, Australia. Retrieved from https://collections.museumvictoria.com.au/items/229755
Natural Pigments. (2018). Cold cinnabar (coarse) pigments. Retrieved from https://www.naturalpigments.com/cold-cinnabar-coarse-pigment.html
New South Wales Department of Primary Industries. (2007, February). Mining by Aborigines: Australia's first miners. Retrieved from http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/109817/mining-by-aborigines.pdf
Paterson, N., & Lampert, R. J. (1985). A central Australian ochre mine. Records of the Australian Museum, 37(1), 1-9. https://doi.org/10.3853/j.0067-1975.37.1985.333
Roth, H. L. (1899). The Aborigines of Tasmania (2nd ed.). Halifax: F. King & Sons.
Sullivan, C. J., & Öpik, A. A. (1951). Ochre deposits, Rumbalara, Northern Territory. Commonwealth of Australia, Ministry of National Development, Bureau of Mineral Resources, Geology and Geophysics (Bulletin No. 8). Melbourne: Commonwealth of Australia.
Taylor, R. (2011). The polemics of eating fish in Tasmania: The historical evidence revisited. Aboriginal History Journal, 31, 1-26. https://doi.org/10.22459/AH.31.2011.02