Heat and Temperature: Class 7 Study Guide
Heat is energy on the move. Understanding how it travels helps us choose clothes, cook food and design buildings.
Temperature tells how hot or cold something is. It is measured in degrees Celsius (°C) with a thermometer. Heat is a form of energy that flows from a hotter object to a colder one. A big pot of warm water holds more heat than a small cup of boiling water, though its temperature is lower.
A clinical thermometer measures body temperature (normal is about 37 °C) and has a kink to stop the mercury falling back. A laboratory thermometer reads from −10 °C to 110 °C. Read a thermometer with your eye level with the scale, and never use a clinical thermometer for hot water.
Three ways heat travels
| Method | How it works | Example |
|---|---|---|
| Conduction | through a solid, particle to particle | a spoon in hot tea gets hot |
| Convection | in liquids and gases, as warmer parts rise | boiling water, sea breeze |
| Radiation | as waves, no material needed | warmth from the Sun or a fire |
Conductors and insulators
Metals such as copper and aluminium are good conductors of heat, so cooking pots are made of metal. Wood, plastic, air and wool are poor conductors (insulators), so pot handles are plastic and winter clothes trap air. Dark, rough surfaces absorb more radiation; light, shiny surfaces reflect it. That is why we wear light-coloured clothes in summer and why thermos flasks have shiny walls.
With adult supervision.
Wax or pins fall off in order.
Heat moved along by conduction.
Metal vs. wood.
Sea breeze and land breeze
During the day, land heats faster than the sea. Warm air over the land rises and cooler air from the sea moves in: a sea breeze. At night the land cools quickly and the sea stays warmer, so air flows from land to sea: a land breeze. This is convection on a big scale and one reason coastal cities such as Chennai feel cooler in the evening.
Worked example and common misconceptions
Example: A metal bench feels colder than a wooden one at the same temperature because metal conducts heat away from your hand faster. Common misconceptions: thinking temperature and heat are the same, that 'cold' flows into a warm object and that clothes make heat. Safety: be careful with hot water, flames and electrical heaters.
Check your understanding: model answers
1. Conduction. 2. Plastic is a poor conductor, so the handle stays cool. 3. Cool air flowing from the sea to the warmer land during the day.
✨ Key Takeaways
- Temperature measures hotness; heat is energy.
- Heat flows from hot to cold.
- Conduction, convection, radiation.
- Metals conduct; air and wool insulate.
💬 Questions for Discussion & Reflection
- Which method moves heat through a solid?
- Why are pot handles plastic?
- What is a sea breeze?
Print a science experiment report →