come from living things.) Lesson 8Kd: Power and efficiency Learning objectives Exemplar teaching activities Differentiation Resources Maths skills Practical skills Developing Starter: Appliances brainstorm Exploring: Power Resources n/a Students Match Sankey diagrams to simple Ask students to work in groups to list ratings from 8Kd examine situations. all the devices they can that use Use a joule meter Exploring various items of State the meaning of efficiency and electricity (either from cells or from to demonstrate Science. domestic recall some advantages of efficient the mains). Ask them to agree the amount of equipment appliances. categories for the main way in which energy used in a to find their Identify useful and wasted energies. each device transfers energy, then to fixed time by power ratings. Describe whether one machine is more divide their lists into these categories. different pieces of efficient than another. equipment. The Describe what power means, and the Exploring: Power ratings results should be relationship between watts and Students examine various items of linked to the joules/second. domestic electrical equipment to find power ratings of Securing their power ratings. Ask students to the equipment. Use Sankey diagrams to compare find a connection between the type of appliances or processes. energy transfer that the device Calculate energy efficiencies. carries out and its power rating. Explain why the efficiency can never be greater than 100%. Explaining: Drawing Sankey diagrams Exceeding Guide students through the process Use the formula relating power, energy of converting data about energy and time (in W, J and s). transfers into a Sankey diagram. Evaluate energy-saving appliances or modifications. Plenary: Thinking about power and efficiency Odd One Out: electricity, heating, chemical. (Possible answers: chemical is the only one that is used as a name for an energy store; heating is the only one that is both a useful and a wasteful way of transferring energy.)
come from living things.) Lesson 8Kd: Power and efficiency Learning objectives Exemplar teaching activities Differentiation Resources Maths skills Practical skills Developing Match Sankey diagrams to simple situations. State the meaning of efficiency and recall some advantages of efficient appliances. Identify useful and wasted energies. Describe whether one machine is more efficient than another. Describe what power means, and the relationship between watts and joules/second. Securing Use Sankey diagrams to compare appliances or processes. Calculate energy efficiencies. Explain why the efficiency can never be greater than 100%. Exceeding Use the formula relating power, energy and time (in W, J and s). Evaluate energy-saving appliances or modifications. Starter: Appliances brainstorm Ask students to work in groups to list all the devices they can that use electricity (either from cells or from the mains). Ask them to agree categories for the main way in which each device transfers energy, then to divide their lists into these categories. Exploring: Power ratings Students examine various items of domestic electrical equipment to find their power ratings. Ask students to find a connection between the type of energy transfer that the device carries out and its power rating. Explaining: Drawing Sankey diagrams Guide students through the process of converting data about energy transfers into a Sankey diagram. Plenary: Thinking about power and efficiency Odd One Out: electricity, heating, chemical. (Possible answers: chemical is the only one that is used as a name for an energy store; heating is the only one that is both a useful and a wasteful way of transferring energy.) Exploring: Power ratings Use a joule meter to demonstrate the amount of energy used in a fixed time by different pieces of equipment. The results should be linked to the power ratings of the equipment. Resources from 8Kd Exploring Science. n/a Students examine various items of domestic equipment to find their power ratings.