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Teacher guide: Year 8 Physics

Energy that is moving and energy that is stored, how it moves from place to place and changes type, and following it through a whole system. Concept tutorials with a roller coaster and energy flow diagrams.

Open the student course

Each lesson works two ways. Students can work through the online tutorial at their own pace (it checks their answers and saves their progress in their browser), or you can teach it to the whole class from the slides, then send students into the tutorial for the Modify and Make steps.

Every lesson guide has plain-language notes, the answers to every check, a solution for every task, and slides and a worksheet for Waypoints Prepare. These guide pages are not linked from student pages, but they are not secret either: keep printed Teacher editions for answers you do not want students to find.

Energy transfer and transformation

Kinetic and potential energy, transfers and transformations, by-product heat and flow diagrams (AC9S8U05).

Energy transfer and transformation in 5 minutes (read before teaching this unit)

The idea in plain words

Energy comes in two families. Kinetic energy is energy of activity: movement, heat (thermal), sound, light and electrical. Potential energy is stored: chemical (food, fuel, batteries), gravitational (height) and elastic (stretched or squashed). How much is stored depends on height and mass, how far something is stretched, or what it is made of.

  • A transfer moves the same type of energy to a new place (heat into your hands).
  • A transformation changes its type (chemical → electrical → light in a torch).
  • Almost every transformation also makes by-product heat (and often sound). It isn't destroyed: it spreads into the surroundings. This is the foundation of efficiency in Year 9.
  • A flow diagram follows energy stage by stage: boxes, arrows for each transfer or transformation, side arrows for by-products.

Where the picture breaks

  • The kinetic and potential families follow the progression; some texts describe energy "stores" and "pathways" instead. The idea that matters is active versus stored.
  • The roller coaster's friction is a steady force; real air resistance grows with speed.

Common misconceptions

  • Things that aren't moving have no energy.
  • Energy is used up, or destroyed by friction.
  • A device makes only its useful output.

Investigate in class

Optional ideas if you run a practical for this unit: pick one, adapt it to your equipment, or use your own.

  • Does the drop height change how high a ball bounces? Change: drop height (25, 50, 75, 100 cm). Measure: the top of the first bounce. Keep the same: the ball, the floor, letting go without a push. (It never returns to its start: ask where the rest went.)
  • Does a higher ramp send a marble further along the floor? Change: the height of the start of the ramp. Measure: the distance it rolls after the ramp. Keep the same: the marble, the ramp, the floor. (Gravitational to kinetic energy, then heat and sound.)
  • Does stretching a rubber band further launch a toy car further? Change: the stretch (2, 4, 6, 8 cm). Measure: the distance the car travels. Keep the same: the band, the car, the surface.

Safety and ethics: launch along the floor, away from faces, and wear safety glasses when stretching bands; pick up marbles so no one slips.