Standards
Exerpted from the Ontario Curriculum Grades 1-8 Science and Technology.
GRADE 7 | UNDERSTANDING EARTH AND SPACE SYSTEMS
HEAT IN THE ENVIRONMENT
OVERVIEW
Heat energy plays a critical role in natural processes and in human life. Global warming has also focused considerable attention on the processes that control temperatures at the earth's surface. By acquiring a working understanding of the nature of heat, students in Grade 7 will gain new insights into the ways that heat affects our world. Students will learn about the causes and effects of heat, investigate its properties, relate it to geological and meteorological processes, and use their new-found knowledge to design a device to minimize heat transfer. They will also use the particle theory to help them explain their observations.
Experiments with heat require that students identify and explain the importance of practices that ensure their personal safety and the safety of others. This includes knowing why very hot water should always be carried in a closed container (e.g., an insulated flask) and why they should stand when heating things and hold objects that are being heated well away from themselves.
Fundamental Concepts: Energy
Big Ideas: Heat is a form of energy that can be transformed and transferred. These processes can be explained using the particle theory of matter. (Overall expectations 2 and 3)
Fundamental Concepts: Sustainability and Stewardship
Big Ideas: There are many sources of heat. (Overall expectation 3)
Fundamental Concepts: Systems and Interactions
Big Ideas: Heat has both positive and negative effects on the environment. (Overall expectation 1)
OVERALL EXPECTATIONS
By the end of Grade 7, students will:
1. assess the costs and benefits of technologies that reduce heat loss or heat-related impacts on the environment;
2. investigate ways in which heat changes substances, and describe how heat is transferred;
3. demonstrate an understanding of heat as a form of energy that is associated with the movement of particles and is essential to many processes within the earth's systems.
SPECIFIC EXPECTATIONS
1. Relating Science and Technology to Society and the Environment
By the end of Grade 7, students will:
1.1 assess the social and environmental benefits of technologies that reduce heat loss or transfer (e.g., insulated clothing, building insulation, green roofs, energy-efficient buildings)
Sample guiding questions: (a) Insulated clothing protects our bodies and increases our ability to enjoy outdoor activities in winter. What science and technology concepts are at work in coats designed for use in cold weather? Who might be interested in such designs?
(b) A well-insulated home is more comfortable and costs less to heat. Reducing heat loss saves energy, and saving energy reduces the environmental impact of energy production. What are some areas of your home where heat might be lost? How can this heat loss be counteracted? What are the benefits of doing so?
(c) Green roofs save on heating and cooling costs and reduce the amount of insulation that is needed. But they have not gained wide acceptance in Ontario. What might be some deterrents to having a green roof? How might these deterrents be overcome?
(d) Energy-efficient buildings are extremely airtight compared to conventionally constructed buildings. This minimizes the amount of warm (or cool) air that can pass through the structure. What are some of the disadvantages to having airtight buildings (e.g., lack of fresh air, moisture buildup)? How can these problems be solved (e.g., through mechanical ventilation systems with heat recovery and humidity control), and how effective are the solutions?
1.2 assess the environmental and economic impacts of using conventional (e.g., fossil fuel, nuclear) and alternative forms of energy (e.g., geothermal, solar, wind, wave, biofuel)
Sample issues: (a) Your family is building a new home. Present a case for installing a geothermal heat pump. In your discussion, be sure to include the benefits and costs from both an environmental perspective and an economic perspective.
(b) Make a case for (or against) using rural land or marginal land-use areas for wind turbine farms.
2. Developing Investigation and Communication Skills
By the end of Grade 7, students will:
2.1 follow established safety procedures for using heating appliances and handling hot materials (e.g., use protective gloves when removing items from hot plates)
2.2 investigate the effects of heating and cooling on the volume of a solid, a liquid, and a gas
2.3 use technological problem-solving skills (see page 16) to identify ways to minimize heat loss
Sample problem: Use the materials provided to create a product (e.g., a model of a piece of winter clothing, a model of a wet suit, a model travel mug for a hot beverage or food item) that will minimize heat loss
2.4 use scientific inquiry/experimentation skills (see page 12) to investigate heat transfer through conduction, convection, and radiation
Sample problem (conduction): After letting spoons made of different materials sit partially submerged in a container of hot water, measure the temperature of the parts sticking out of the water. What conclusions can you draw from your findings?
2.5 use appropriate science and technology vocabulary, including heat, temperature, conduction, convection, and radiation, in oral and written communication
2.6 use a variety of forms (e.g., oral, written, graphic, multimedia) to communicate with different audiences and for a variety of purposes (e.g., using the conventions of science, create a labelled diagram to illustrate convection in a liquid or a gas)
3. Understanding Basic Concepts
By the end of Grade 7, students will:
3.1 use the particle theory to compare how heat affects the motion of particles in a solid, a liquid, and a gas
3.2 identify ways in which heat is produced (e.g., burning fossil and renewable fuels, electrical resistance, physical activity)
3.3 use the particle theory to explain the effects of heat on volume in solids (e.g., rails, sidewalks, and bridge segments expand in hot weather), liquids (e.g., sea levels are rising partly because global warming is making the oceans warmer and the water in them is expanding), and gases (e.g., the air in car tires expands on hot pavement)
3.4 explain how heat is transmitted through conduction (e.g., the transmission of heat from a stove burner to a pot and from the pot to the pot handle), and describe natural processes that are affected by conduction (e.g., the formation of igneous and metamorphic rocks and diamonds)
3.5 explain how heat is transmitted through convection, and describe natural processes that depend on convection (e.g., thunderstorms, land and sea breezes)
3.6 explain how heat is transmitted through radiation, and describe the effects of radiation from the sun on different kinds of surfaces (e.g., an ice-covered lake, a forest, an ocean, an asphalt road)
3.7 describe the role of radiation in heating and cooling the earth, and explain how greenhouse gases affect the transmission of radiated heat through the atmosphere (e.g., The earth is warmed by absorbing radiation from the sun. It cools by radiating thermal energy back to space. Greenhouse gases absorb some of the radiation that the earth emits to space and reradiate it back to the earth's surface. If the quantity of greenhouse gases in the atmosphere increases, they absorb more outgoing radiation, and the earth becomes warmer.)
3.8 identify common sources of greenhouse gases (e.g., carbon dioxide comes from plant and animal respiration and the burning of fossil fuels; methane comes from wetlands, grazing livestock, termites, fossil fuel extraction, and landfills; nitrous oxide comes from soils and nitrogen fertilizers), and describe ways of reducing emissions of these gases