Light Waves

The Light Waves unit helps students gain a deeper understanding of how light interacts with materials and how these interactions affect our world, from the colors we see to changes caused by light from the sun, such as warmth, growth, and damage.

In this unit, students investigate a specific change caused by light: skin cancer. Australia has one of the highest skin cancer rates in the world: More than half of the people who live there will be diagnosed with skin cancer in their lifetime. Scientists have investigated the factors that place Australia’s population at such an exceptionally high risk of skin cancer. They have found that less ultraviolet light is absorbed as it passes through the atmosphere above this region due to ozone depletion. They have also found that the Australian population is more susceptible to skin cancer because of the large proportion of people with light skin tones. This is because people with lighter skin tones have less melanin in their skin cells than people with darker skin tones. Melanin absorbs ultraviolet light before it damages genetic material inside skin cells, providing some protection against damage caused by light from the sun. Therefore, people with low levels of melanin in their skin cells are at a greater risk of developing skin cancer than people with higher levels of melanin in their skin cells.

Taking on the role of student spectroscopists working for the fictional Australian Health Alliance, students investigate why Australia’s cancer rate is so high, analyzing real data that scientists might consider. This problem serves as the anchor phenomenon that students focus on throughout the unit. Students use the Light Waves Simulation, conduct hands-on activities, read articles, and watch videos to gather evidence about how light interacts with materials. The Sim allows students to observe how light carries energy and how this energy causes materials to change when it is absorbed. Students can simulate manipulating the wavelength of light, observing that different types of light have different wavelengths and that different types of light can change a material in different ways. Students also learn that when energy from light is not absorbed by a material, it can be either reflected or transmitted. Students apply these ideas to construct an argument explaining the high skin cancer rate in Australia, citing both low ozone levels in the atmosphere and low levels of melanin in the population.