Science / Year 8 / Science as a Human Endeavour / Use and influence of science

• TLF-IDM020213

Visual art and science are often considered to be separate fields. Watch as Phred Petersen talks about the way he combines his passions of photography and science. What is the role of technology in enabling this crossover? What kinds of scientific discoveries can be assisted by high-speed photography? And how can scientific ...

• TLF-IDM021125

What does 'horsepower' really mean? And how do engines work? Join Luke and Abhi from MIT to find out! As Abhi explains, engines produce power by forcing a mixture of fuel and air into a tight space and then burning it. Piston engines and turbine engines do this in similar, yet different ways. After watching this video, ...

• TLF-IDM021121

Figuring out how to clean up contaminated rivers is a big challenge. It's also tricky to work out where the most contaminated parts of a river system are and whether its fish are safe to eat. Watch this video and learn how engineering has helped to solve these problems. Why do you think engineers looked to the bottom of ...

• TLF-IDM016119

This engaging article outlines the science behind the sense of smell. It explains what makes dogs' noses and their sense of smell so powerful. It also describes how understanding the science has had implications for the potential development of new technologies.

• TLF-IDM017136

This is a video about water availability for people living in the Peruvian Andes. It includes vision and information about water scarcity in this region and details of a Food and Agriculture Organization of the United Nations funded project involving the creation of a sustainable water management program. The program involves ...

• TLF-IDM016438

Explore options for houses, work, food and transport in 2024 in this multimedia presentation from Radio National. A useful resource for stimulating discussion about applications of science and implications for society and the environment as well as current issues and developments in science. Gives examples of how different ...

• TLF-IDM015218

This is a video clip of a TEDMED speaker, Howard Shapiro, presenting ideas about improving the nutritional value of plants to address malnutrition and the food requirements of a growing world population. The clip emphasises that poor nutrition has negative health and developmental effects on children, particularly those ...

• TLF-IDM017102

This is a website about the environmental and animal welfare issues related to the consumption of meat. It contains sections on the amount of meat we eat; the environmental impacts of consuming meat; cattle, chicken, egg-laying-hen and pig-farming factories; and what can be done to improve the current state of the meat ...

• TLF-IDM017137

This is a video about the progress towards food and water security in Afghanistan. It includes images and information about how the global economic crisis has affected the people of Afghanistan; the value of investment in agriculture production to reduce poverty in this region; and a water security project that is jointly ...

• TLF-IDM020774

This is a video (4:09 min) about the University of New England’s Kirby Research Station and how its work with sheep has been transformed by technology, particularly the Radio Frequency Identification (RFID) tag. The video is presented by members of the Enhanced sheep wellbeing and productivity research program and includes ...

• TLF-IDM016584

This program gives an update on research into solar thermal electricity. Liddell Power Station in the Hunter Valley, NSW is a hybrid power station using solar energy to pre-heat water and so reduce the use of coal and the production of carbon dioxide. Some scientists claim that harnessing the solar heat in an area 50km ...

• TLF-IDM019316

This comprehensive web resource provides a series of six interactive slide shows (chapters) that introduce the cause and impacts of tsunami with a focus on Australia, Asia and Pacific regions. Produced by experts in the field, this information is clearly and simply described. The engaging presentation is enriched with photography, ...

• TLF-IDA002815

Creating a wildlife habitat can provide a home for a variety of local wildlife from the smallest insects and spiders to birds, reptiles, mammals and frogs. These habitats can provide a sanctuary for species that have been displaced through urbanisation, as built structures replace natural areas. The Vision activity determined ...

• TLF-IDA002816

This learning activity is the second part of a sequence of 5 individual learning activities focused on creating a wildlife habitat. The order of these learning activities are: research, vision, design, planting and monitoring and care. OUTCOMES for this learning activity are for children to: create a vision of what their ...

• TLF-IDM015344

Interactive game to be played following the 'What is energy?' Notebook and assessing students' knowledge of energy sources - renewable and non-renewable and the possible effect on the environment. The game may be played by two groups on IWB, or pairs of students on a computer.

• TLF-IDM015317

A webpage of links to a range of interactive online resources about mining and mineral extraction, with a focus on uses of copper and environmental rehabilitation after mining.

• TLF-IDM015353

A webpage with information and resources on how the traditional knowledge of Aboriginal and Torres Strait Islander peoples is being used to make better land management decisions. Fire-stick farming is demonstrated and explained.

• TLF-IDM016398

An interview and lab tour with Dr Martina Doblin, a phytoplankton ecologist at UTS. Martina talks to students and their teacher from Concord High School about her work studying microscopic organisms such as the toxic algae that make up harmful algal blooms.

• TLF-IDM016406

This nine and a half minute video segment from Catalyst describes how researchers from Monash University have hard evidence that cloud seeding can produce good amounts of extra rainfall. Data collected over a long period of time has give hope to scientists and environmentalists who are trying to reduce the impacts of droughts ...

• TLF-IDM019742

This is a unit of work on engineering, the range of possible occupations in engineering and the future and ethics of engineering. The resource includes: An introduction with teacher notes, student tasks, embedded videos and links to additional resources. The resource aims that students learn broadly about engineering and ...

• TLF-IDM019058

This lesson sequence examines the role that river operators play in water resource management in the Murray-Darling Basin and explains how they direct water releases and track progress downstream for environmental watering and flood management. It includes a teacher PowerPoint presentation, separate teacher notes and a ...

• TLF-IDM016491

This ABC In Depth feature article discusses the projections of how long will our energy resources will last given that our need for fossil fuels is insatiable, but coal, oil, gas and uranium reserves are finite and some may even be in decline. This article is comprehensive, but it is dated at 2008.

• TLF-IDM016628

In this resource students work as scientists while exploring their local environment in the real world of scientific endeavour. Games and animations are used to model the real experience of investigating a freshwater lake. This version of the Macrobiotica resource has been modified for Internet use by removing Teaching ...

• TLF-IDM018950

This is a unit of work about how cotton, timber and wool are produced, processed and brought to customers in Australia. It explores: where cotton, timber and wool comes from; past, present and future production systems; and a range of other related topics including land management, water management, waste management, revegetation, ...

• TLF-IDM019978

This is a unit of work about forensic science, the occupations that use forensic science and the future and ethics of forensics. The resource includes: An introduction with teacher notes, student tasks, embedded videos and links to additional resources. Specific topics explored include what is forensic science and how ...

• TLF-IDM020885

This thermal comfort learning resource will guide students through an extended school based investigation. Students will develop and implement a chosen sustainability action and then evaluate and reflect on their success and their learning.

• TLF-IDM020816

This is a unit of work that focuses on improvements in livestock and crop production brought about by agricultural practice, scientific research and technology. The unit is organised around six learning experiences that include investigating how agricultural products have developed over time; identifying the role of technology ...

• TLF-IDM019382

This is a video about plant breeder and nursery owner Brian Fitzpatrick and his work of breeding waratahs. It shows scenes of his activities in the Waratah Australis Nursery as he speaks of the magnificence of waratahs; the stages in the breeding process including hand-pollination and the production of 12,000 seedlings ...

• TLF-IDM019976

This is a unit of work about the scientific techniques and ethical considerations in art conservation and the occupations that exist in art conservation. The resource includes: An introduction with teacher notes, student tasks, embedded videos and links to other resources. Specific topics explored include what art conservators ...

• TLF-IDM019938

This is a unit of work about military science, the occupations that use military science and the future and ethics of this technology. This resource aims to have students think about the people who work in military science (who they are and what it is they do); and to begin to consider the purpose of military science (that ...

• TLF-IDM020088

This study guide examines ways Australian cattle and sheep farmers are monitoring and researching how greenhouse gas emissions are being produced by farms and steps farmers use to reduce them. This includes selective breeding programs to produce cattle and sheep whose digestive processes emit less methane, research into ...

• TLF-IDL2562

See how scientists such as Ernest Rutherford have investigated the structure of atoms. Explore possible models. Fire charged particles at atoms and find which model best fits the results. This learning object is one in a series of six objects. Three of the objects are also packaged as a combined learning object.

• TLF-IDM015837

Australia has a long and proud history of excellence in science. How should we celebrate this? Watch this clip to find out about an Australian organisation that recognises and promotes outstanding scientific achievement. You'll also find why its Canberra headquarters is referred to as 'the flying saucer'!

• TLF-IDM020210

When it comes to dropping food, have you heard of the 5-second rule? Or the 3-second rule? Watch this video to learn what really happens when you drop food. In order to cause disease, what must bacteria do? What circumstances allow bacteria and viruses to contaminate food more successfully?

• TLF-IDM021116

Good question! Find out whether this is possible by watching as biologist at MIT, Dr Sera Thornton explains. What is a genome? And why do genomes need to be decoded? If the rhino genome was successfully decoded and the part that described the rhino horn was isolated, what would the process be for creating a unicorn?

• TLF-IDM020192

What are microbes? What are the four major groups that most microbes belong to? Listen as Dr Taghrid Istivan explains where microbes are found. What is the name of the group of microbes she describes as beneficial to our health? Can you explain what happens when people get food poisoning?

• TLF-IDM020605

Listen to electrical engineering student Kulsoom Hussain describe her dream career. What are some of the challenges she says she'll face in trying to achieve her goals? What can you find out about the energy sources used in Australia? How much renewable energy is used to power our country?

• TLF-IDM016153

Scientists have confirmed the presence of water on the moon. Rather than occurring in rivers or lakes, water is found sparsely mixed amongst rocks. It's suggested the water came from comets, or the combination of incoming protons with oxygen. Jonathan Nally described the latest experiments where spacecraft will be sent ...

• TLF-IDL2357

Select energy sources and energy converters to build energy chains to power appliances and vehicles. Examine how each energy converter in a chain loses some energy and reduces the energy available for use. For example, show that using a solar panel and an electric motor to drive a car delivers only 16% of the original ...

• TLF-IDM020685

Did you know that climate change is not a recent phenomenon? In the past, natural events led to changes in the climate. Although natural events still affect climate, they're not enough to explain the big changes we've been seeing in the last 150 years. What changes on earth can account for such dramatic changes to our climate? ...

• TLF-IDL5774

Control the motion of the Earth in its orbit around the Sun. Work out how the Earth’s orbit and the tilt of its axis determine seasons in the different hemispheres. Work out how the Earth’s orbit and the tilt of its axis determine day length in the different hemispheres. Examine the heating effect of the Sun. Compare seasons ...

• TLF-IDM016726

This brief ABC News in Science article from 2009 explains that asteroids become redder the longer they stay out in the sun because of the solar wind. Scientists are using this to try to find our more about our planetary origins.

• TLF-IDM017570

Travel back in time in outback Australia and investigate the giant lumbering beasts of the past - the megafauna. Visit a fossil site in Cuddie Springs, New South Wales, where megafauna bones have been discovered. Explore the connection between Aboriginal peoples and megafauna, and theories for the extinction of Australia's ...

• TLF-IDM016629

This 5 minute video segment from Catalyst highlights the vulnerability of some of our ecosystems and the way abiotic factors can have a dramatic effect. It also exemplifies the difficult process of having new scientific ideas accepted.

• TLF-IDM016775

This 9 minute video segment from Catalyst shows how inspiration from the world of animals has helped in the mechanical design of robots and adhesive materials.

• TLF-IDM016656

An interview with Adam Cawley, a chemist and scientist from the Royal Australian Chemical Institute, who is an expert in drug testing in sport. Adam talks to a teacher from Killara High School about working as a chemist, and the challenges in drug testing.

• TLF-IDM016404

This web page is designed to help students to understand the history of biotechnology and how it contributes to solving real-world problems such as disease and waste disposal.

• TLF-IDS4975

These seven learning activities, which focus on 'visual representations' using a variety of tools (software) and devices (hardware), illustrate the ways in which content, pedagogy and technology can be successfully and effectively integrated in order to promote learning. In the activities, teachers assist students to understand ...

• TLF-IDS7066

This teacher resource describes a pilot project in which selected Victorian science teachers learnt functional and systemic pedagogical strategies to support English as an Additional Language (EAL) students to understand and use science literacy genres. Organised in nine sections: Summary; Target student group; Method; ...

• TLF-IDM015668

What does spinifex grass contain that might prove useful in modern buildings? Watch this clip and discover how Aboriginal knowledge, combined with Western science, is unlocking the potential of spinifex. Find out about this natural resource and how it could become a new, sustainable material for the building industry.

• TLF-IDM015808

Explore with the Surfing Scientist team what happens when metals are heated and cooled. Find out what happens to a metal ring when it is immersed in extremely cold liquid nitrogen. What do hinges on the Sydney Harbour Bridge have to do with all this? Find out.

• TLF-IDM025393

Much of the world’s population will eventually have to deal with the consequences of sea-level rise, but the question is: how high will the water get? Dr Graham Phillips investigates how scientists are turning to the distant past to predict the impact of rising sea levels. Watch scientists explore 120,000-year-old coastlines, ...

• TLF-IDM015378

Find out why European carp fish are called 'river rabbits' in Australia. Listen to how they came to Australia and what makes them such a pest now.Discover how a local entrepreneur is exploiting the new resource while scientists are doing their best to cap the carp population explosion.

• TLF-IDM015950

Want to find out what happens when you drop a watermelon and an apple from the top of a building? In this clip, Bernie Hobbs and Ruben Meerman, investigate whether the mass of an object influences how fast it falls. Bernie and Ruben ride the 'Giant Drop' at Dreamworld, drop a watermelon and apple from an eighth floor balcony, ...

• TLF-IDM018842

Many natural products, such as red cabbage and turmeric, can be used as a natural source of colour to dye fibres. Watch the dyeing demonstration in this clip to see how. Discover the chemistry of natural dyes, including the bonding properties of different pigments and how acid-base reactions can alter the colour of pH-sensitive ...

• TLF-IDM025065

Demand for certain kinds of food changes with time as people's tastes change. Avocados were not always popular, but in recent years their popularity has increased so much that supply cannot keep up with demand. Learn how stem cell scientists at the University of Queensland are leading the way in research that could cut ...

• TLF-IDM025384

Bee populations around the world have started vanishing, in a process known as colony collapse disorder. Scientists have many ideas about what causes colony collapse, including one possible culprit: the varroa mite. Australia is one of the last places on Earth unaffected by varroa. Could this mean that Australia could have ...

• TLF-IDM020570

How many different paper plane designs are there? Lots! Watch as Dylan Parker, paper plane expert, demonstrates some of his favourites. Notice the way the different shapes and features of the planes cause them to move through the air in different ways. Which one do you like the most? Why not have a go at making something similar?

• TLF-IDM020914

You can find both refracting and reflecting telescopes at Sydney Observatory. How are they different in the way they work and look? What can you find in nature that is like a telescope? Which type of telescope is it like?

• TLF-IDM019407

This video supports the unit of work by the same name. Presented by a classroom teacher who has trialled the unit the video reflects on the inquiry based pedagogy and the unit's value in terms of curriculum alignment and student engagement.

• TLF-IDM025073

In this learning sequence, students explore a simple particle model for matter, heat energy and thermal expansion. They apply their learning to the context of expansion and contraction of rail lines and investigate ways that this is mitigated in real situations involving rail lines. They subsequently explain this to young ...

• TLF-IDM015400

Imagine our world if nuclear power generation could be made safer. Discover how Chinese scientists have developed a new nuclear reactor that reduces the chances of the reactor overheating to the point of meltdown. To do this the pebble bed reactor uses advances in technology to replace the traditional water-cooled system. ...

• TLF-IDM015531

Discover how nanotechnology is contributing to the creation of new, improved batteries that may soon be used in all our mobile phones and portable music devices - even in cars and trams. Catalyst's Tanya Ha looks at how traditional batteries produce electricity and how their efficiency may be increased by tiny devices known ...

• TLF-IDM021137

We don't normally associate robotics with farming but, in fact, robotics have revolutionised farming and agriculture in recent years. Find out how some strawberry farmers are using drones to disperse 'good' bugs for pest control management. Can you think of some other ways drones could be used to help farmers?

• TLF-IDM015553

Will a medicine ball or a basketball hit the ground first when dropped at the same time from the same height? In this clip, Catalyst's Dr Derek Muller investigates what influences the speed at which objects fall. Derek challenges some people in a market to make a prediction and explain their thinking, before he finally ...

• TLF-IDM025061

There are already more people around the world who eat farmed fish than people who eat beef. With the world's population and demand for food increasing, why is it so important for us to farm sustainably? One fishery near Kakadu in the Northern Territory practises sustainable farming. Find out what makes this farm so sustainable.

• TLF-IDM016022

Discover what threatens a native Australian predator and how scientists are hoping to save it from extinction. This clip about quolls in the Northern Territory describes the causes of its decline and a rescue strategy to save it from extinction. The strategy has a surprising twist - it features the very thing that is threatening ...

• TLF-IDM015401

Explore how chemical pollutants affect the Antarctic food web. A scientist shows that baleen whales are consuming Antarctic krill contaminated by accumulated residues of persistent organic pollutants (POPs) from pesticides and industrial chemicals. Find out why these pollutants are concentrated at the Earth's polar regions.

• TLF-IDM020430

Do you know what you want to be when you grow up? Debora Fairbrother, a NASA engineer, didn't know what career path she was on. Watch this clip as she talks about the importance of education and of following your passion.

• TLF-IDM008836

Find out how emissions from coal-burning can be reduced by turning the coal into syngas. This is a fact sheet describing methods of coal gasification, and how the resulting syngas can drive a combined cycle power generator. It lists the advantages of the technology, including lower emissions and increased efficiency, as ...

• TLF-IDM008851

Find out about the technologies that can reduce our greenhouse-gas emissions. This resource consists of an animated video accompanied by an interactive landscape activity. The video focuses on technologies that can reduce carbon-dioxide emissions from the burning of fossil fuels, as well as renewable energy and improved ...

• TLF-IDM008839

This is an activity sheet providing instructions for a simulated mining experiment using pieces of fruitcake. Students use various tools to remove different fruits, each representing different minerals, from a piece of fruitcake which represents the mine site. They are then required to rehabilitate the 'mine site'. The ...

• TLF-IDM008854

Find out how copper ore is extracted and turned into copper metal. This is a PowerPoint presentation showing the properties, uses and extraction of copper. It includes details of the mining and processing of copper ore, as well as smelting, converting and refining to produce copper metal. Most slides contain photographs ...

• TLF-IDM008865

This interactive activity allows students to explore the processes involved in the mining and processing of copper ore and the production of copper. Students initially put the processes in the correct sequence and then select each stage to animate it and access relevant information. The smelting stage includes an activity ...

• TLF-IDM008845

This is a teaching unit, designed for year 10, aimed at engaging students in investigations about low-emission energy sources. A unit outline, teacher guidelines, student activity and an assessment task are provided.

• TLF-IDM008868

This Google Earth interactive map shows the locations of operating mines in Australia. Each location is represented by name and an icon corresponding to the commodities extracted. Select an icon to view key information about the commodities, the operator and location of the mine.

• TLF-IDM008847

This fact sheet provides information about how coal seam gas or methane is extracted and used as an energy source. It describes several coal seam gas operations in the Bowen and Surat Basins in Queensland. Several photographs and a map of projects in the Surat Basin are also included.

• TLF-IDM008859

Find out how carbon emissions from power generation can be reduced. This is a PowerPoint presentation that deals with the contribution carbon capture and storage can make towards reducing greenhouse gas emissions. It explains the carbon cycle and the greenhouse effect. Techniques of carbon capture are described and their ...

• TLF-IDM008869

This Google Earth interactive map shows the locations of all operating and proposed renewable energy power stations in Australia. Each location is represented by name and an icon corresponding to the type of energy used. Select an icon to view key information about the ownership and location of the facility.

• TLF-IDM012555

This is an online resource about the causes of volcanoes, part of a larger resource about volcanoes. It includes sections on the Earth's tectonic plate margins spreading, the Earth's tectonic plate margins subducting, and predicting volcanic eruptions. The image at the top of the screen illustrates the inside workings of ...

• TLF-IDM015290

This resource is designed to support science teachers in addressing concepts in electricity in the BOS NSW Syllabus for the Australian Curriculum in Science - Stage 3. Making decisions about the use of electricity is approached from an understanding of circuits, sources and sustainability.

• TLF-IDM008840

This is an information sheet containing a student activity simulating geological sequestration of carbon dioxide as well as background information for teachers. The background information describes sequestration in geologic formations, including oil and gas reservoirs, unmineable coal seams and deep saline reservoirs. The ...

• TLF-IDM008861

Identify how mines affect the environment and investigate ways of reducing the effects. This student worksheet comprises a diagram showing activities at a mine site and a table to be completed by the student. Students use the table to summarise environmental effects of the mine and the actions taken at the site to reduce ...

• TLF-IDM008885

This is a colour video clip of marine scientist Dr Candida Savage discussing nutrient run-off from farmland, and the effects it has on estuaries and other coastal environments. The clip shows Dr Savage, from the University of Otago, New Zealand, being interviewed. It also shows images of houses on the banks of estuaries, ...

• TLF-IDM025824

This resource provides a scaffold for students to analyse the features of a Queensland animal and relate them to its survival success. Students then conduct the animal design challenge: Engineering new features for their animal to increase its chance of survival and future success. Students also make predictions about how ...

• TLF-IDM017167

This is a video about the valuable genetic diversity of Asia's indigenous domesticated animals; the contribution the animals' genes make to local people's food security; and the results of the use of genetic technologies. The video identifies ever-present links between farmers, their animals and the environment by describing ...

• TLF-IDM020698

This is a detailed plan for teaching a unit on coral bleaching. It includes a unit outline, overview and aim, learning outcomes, inquiry questions, background information about coral bleaching, lesson plans and a guide to assessment. The lesson sequence is based on the inquiry based 5Es approach to teaching Science, with ...

• TLF-IDM025724

A collection of geography and science resources for high school teachers and students to support teaching and learning from home. The resources were developed by Department of Education teachers from 25 Environmental and Zoo Education Centres in NSW and include Google Sites, programs and activities.

• TLF-IDM008764

This is a colour photograph of a scientist in a laboratory using a laptop computer to download data from electronic animal tags. To the right of the computer is a specialised communication box into which the electronic tag is placed. The scientist in the image is Dr Miles Lamare, a marine biologist involved in sea star ...

• TLF-IDM021053

This library provides a series of one to two page fact sheets on a range of topics related to the Australian cotton industry including: an overview of the industry, history of the cotton industry in Australia and in the world; economics of Australian cotton; biotechnology; climate challenges and cotton; properties of cotton ...

• TLF-IDM012215

This is an interactive teaching and learning resource that years 7 to 10 secondary school students can use to simulate the motion of a skateboarder descending and ascending on a variety of tracks. Height, speed and energy conservation are visually displayed. The skater's mass and starting height, as well as the drag he ...

• TLF-IDR3465

This is a black-and-white photograph measuring 18.7 cm x 24.5 cm, showing three Malay or Indonesian men grading and sorting mother-of-pearl shells in Broome, Western Australia in about 1953. The photograph was taken by the famous Australian photographer Frank Hurley.

• TLF-IDR3048

This is a black-and-white photograph of the exterior of an exhibition home made of fibrolite (fibro-cement) that was constructed by James Hardie and Co Ltd (now known as James Hardie Industries). The street outside the home is crowded with people, some of whom have come to view the fibrolite home. The photograph measures ...

• TLF-IDL696

Watch an animation of the Earth rotating in space showing day and night, the equinox where locations on Earth experience close to equal hours of daytime and night-time (12 hours) and views of the Earth from above the North and South Poles. Turn an animated model of the Earth to explore how rotation is related to night and ...

• TLF-IDR6881

This is a colour photograph of a 'Zygomaturus tasmanicus' fossil skeleton. The skeleton is a museum specimen and has been braced with metal rods. It is displayed in a standing posture.

• TLF-IDR6871

This is a colour photograph of a fossil of a gastropod 'Tenagodus occlusus', showing the spiralled shell.

• TLF-IDM015397

Imagine what would happen if a deadly fish disease found its way into Australia's biggest river system. Watch this clip to learn more about a disease threatening the ecology of the Murray-Darling River. Scientist, Professor Richard Whittington, explains that the disease could be the final straw for an endangered Australian ...

• TLF-IDM015968

Did you know that Australia is the most flammable continent on Earth? Watch this clip to discover how bushfires impact natural ecosystems, and how the increasing global threat of bushfires may affect Australia. Australian scientists explain the ecological consequences of fire and a US expert describes his concerns for the future.

• TLF-IDM025103

The koala population in rural NSW has been declining over the years due to drought and heatwaves. What causes some of the temperature extremes experienced in this region? Dr Mella believes koalas normally get most of the moisture they need to stay hydrated from eucalyptus leaves. What has changed in recent years that means ...

• TLF-IDM025383

Find out how carbon dioxide makes the Earth warmer, how oceans store heat and the way we can see climate history in ice. What are the consequences of changes in the global climate? What can we do as individuals and communities to stop these negative changes?