Energy can't be created or destroyed

ScienceEnergyAges 11–12

Explain the principle of conservation of energy (energy cannot be created or destroyed, only transferred between stores), and describe how energy is dissipated as thermal energy to the surroundings in all real processes

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Teaching Table

Set out your lesson

Track useful and dissipated energy without making any energy disappear.

Activity

Name one energy store and one transfer pathway. Ask where energy goes when a moving toy slows. If stores and pathways are confused, revisit the two hard prerequisites first.

If Not Ready

Pause and explicitly teach or revisit the named hard prerequisite; do not treat its allocation or authored status as learner readiness.

About 20 minutes. Use Show, G and T1 cards on screen, scrap paper and a pencil. No real charger or powered device. Show one card at a time; put models and adult key aside before Try.

Use the supplied paper cases only unless the optional paper prototype test is explicitly chosen. Do not handle electrical chargers, heat materials, mix chemicals, approach floodwater or volcanoes, or disturb animals. For the optional prototype, an adult checks a clear tabletop; use only paper and a blunt pencil, keep paper away from faces, and stop if the setup feels unsafe. Missing equipment, discomfort or no test means not performed: leave observations blank. No personal health, disaster or family experience is required.

Retain your actual plan and observations on paper between steps. If not performed, leave results blank. Record response mode and assistance; do not infer mastery.

Use the complete materials on screen or print only the current sheet. Keep adult guidance out of learner view. Retain an earlier model only when the current step supplies it as context.

Teaching limits and safe use

These are finite task opportunities, not proof of mastery. Record what was attempted and what support was used.

Supplied joules are illustrative, not observed measurements.
Canonical closed-system statement retained in provenance but qualified in teaching.
These bounded source-based examples and task opportunities do not establish learner mastery or general scientific performance.

Retain your actual plan and observations on paper between steps. If not performed, leave results blank. Record response mode and assistance; do not infer mastery.

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Track useful and dissipated energy without making any energy disappear.

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Check understanding

States the law of conservation of energy
Explains why the total energy in a closed system is always the same even though it changes form
Explains what dissipation means and why it happens in real machines (friction, air resistance)
Gives an example showing why 'wasted' energy is not lost but transferred to the surroundings

“If your child charged their phone overnight and was asked where the electrical energy goes, could they explain what conservation of energy means — and why the charger gets warm even though that heat isn’t doing any useful work?”

Curriculum record

Type: Conceptual
Subject: Science
Domain: Energy
Age range: Ages 11–12

Standards

ngss-ms:MS-PS3-5uk-nc-2013:KS3.Sci.Phys.Energy.2