THE TOTAL AMOUNT OF ENERGY

1.1 Description of the scientific concept (according to Wynne Harlen, 2015)

Energy can be transferred from one body or group of bodies to another in various way

Many processes or events involve changes and require an energy source to make them happen. Energy can be transferred from one body or group of bodies to another in various ways. In these processes some energy becomes less easy to use. Energy cannot be created or destroyed. Once energy has been released by burning a fossil fuel with oxygen, some of it is no longer in a form that is as convenient to use.

There are various ways of causing an event or bringing about change in objects or materials. Objects can be made to change their movement by pushing or pulling. Heating can cause change, as in cooking, melting solids or changing water to vapor. Electricity can make light bulbs glow. Wind can rotate the blades of wind turbines.

In all these changes, energy is transferred from one object, which is an energy source or resource, to another. Fuels such as oil, gas, coal and wood are energy resources. Some energy resources are renewable, such as those produced by wind, waves, sunlight and tides, others are non-renewable such as from burning fossil fuels with oxygen.

Energy transmission

Objects can have stored energy. This can be done, for example, by their chemical composition (as in fuels and batteries). Movement, temperature or the position of objects in a gravitational or other field can also store energy. Energy can be stored by lifting an object. When the object is released and falls down, this energy is stored in its motion. When an object is heated, it has more energy than when it is cold. An object at a higher temperature heats its surroundings or cooler objects until all objects reach the same temperature. How fast this happens depends on the kind of material which is heated (and the object was made of) and on the materials between them (heat conductor or heat insulator). A battery stores energy about the chemicals in it. The energy is released when the battery is connected, so that an electric current flows. This transfers the energy to the other components in the circuit and to the environment. Energy can be transmitted in different ways: by radiation, as mechanical force, as sound in air or as light in air and vacuum.

Many processes and phenomena – from the growth of plants to the weather – can be described as an energy exchange. The transfer of energy usually leads to a wider distribution of energy. This process cannot be reversed and the energy of the moving of the particles cannot be easily reused.

Energy cannot be created or destroyed. When energy is transferred from one object to another, the total amount of energy in the universe remains the same. The amount of energy that one object loses is the same another object gains.When the sun heats the earth, the sun gradually loses energy through the radiation that warms the earth and other planets. The mass of atoms is a form of stored energy, also called nuclear energy. Radioactive atoms release this energy, which may become available as heat.

Energy demand

Across the world, the demand for energy increases, as human populations grow and because modern lifestyles require more energy, particularly in the convenient form of electrical energy. Fossil fuels, which are frequently used in power stations and generators, are nonrenewable. In addition, their combustion contributes to global warming and climate change. Therefore, we should find other ways to generate electricity, to reduce the demand and to improve the efficiency of the processes in which we use it.

1.2 What are elementary school students able to understand? (according to Wynne Harlen, 2015)

Elementary school students are already able to experience and understand the following part of this “Big Idea”: There are various ways of causing an event or bringing about change in objects or materials. Objects can be made to change their movement by pushing or pulling. Heating can cause change, as in cooking, melting solids or changing water to vapour. Electricity can make light bulbs glow. Wind can rotate the blades of wind turbines.

In all these changes, energy is transferred from one object, which is an energy source or resource, to another. Fuels such as oil, gas, coal and wood are energy resources. Some energy resources are renewable, such as those produced by wind, waves, sunlight and tides, others are non-renewable such as from burning fossil fuels with oxygen