7th grade · Science · Unit 6 of 18
Heat & Particles
Heat, motion and changing state
What your child practices
Heat as energy linked to particle motion, temperature, expansion and contraction, changes of state, and the ways heat is generated (friction, electricity, burning, chemical reactions and the Sun).
Texas Essential Knowledge and Skills (TEKS) teks student expectation: 7.8(B); 7.8(C) · thermal energy flowing from warm to cool, and temperature and particle motion
How we explain it
Children can open this short lesson before they practice.
- Heating makes particles move faster and spread apart, so most things expand. Cooling makes them contract.
- Temperature measures how fast the particles move on average.
- Heat can come from burning, friction, electricity, chemical reactions and the Sun.
Example: Water is heated from 20 °C to 65 °C. How much did its temperature rise? Subtract the start from the end. 65 − 20 = 45. Answer: 45 °C
Heat & Particles in Texas
In the Texas Essential Knowledge and Skills (TEKS), this is unit 6 of 18 in 7th grade Science, after Moving Heat and before Our Solar System.
Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.
Source: Texas Education Agency (TEA)
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
How is the heat made? Sort each example.
Sort into: 🤲 friction · 🔌 electricity · 🔥 burning
- 🫖an electric kettle
- 🍞a toaster
- 🍳a gas stove
- 🚲brake pads slowing a bicycle
- 🔥a campfire
- 🤲rubbing your hands together
🤲 friction: brake pads slowing a bicycle, rubbing your hands together · 🔌 electricity: an electric kettle, a toaster · 🔥 burning: a gas stove, a campfire
Hint: Friction makes heat when surfaces rub. Electricity can heat a wire. Burning (combustion) is a chemical reaction that releases heat.
Question 2
Your body makes heat mainly from…
- burning fuel inside your stomach
- friction in your shoes
- chemical reactions that release energy from food
- absorbing cold air
chemical reactions that release energy from food
Hint: Cells use food for energy, and some of it is released as heat.
Question 3
Which statement correctly describes heat and temperature?
- Heat is energy that moves from warmer to cooler; temperature measures average particle motion
- Temperature is the energy moving between objects
- Heat measures how fast something is moving overall
- Heat and temperature mean exactly the same thing
Heat is energy that moves from warmer to cooler; temperature measures average particle motion
Hint: Heat is a transfer of energy. Temperature is a measure of an object's particles.
Question 4
At −200 °C, what state is nitrogen?
nitrogen Melting point Boiling point −210 °C −196 °C - liquid
- solid
- gas
liquid
Hint: Below the melting point it is a solid. Between the melting and boiling points it is a liquid. Above the boiling point it is a gas.
Question 5
How does a liquid thermometer work?
- The liquid disappears when cooled
- The liquid turns into a solid
- The tube grows when heated
- The liquid expands when heated and rises in the tube
The liquid expands when heated and rises in the tube
Hint: A warmer liquid takes up more space, so it climbs higher.
Question 6
A pot of water is heated from 18 °C to 58 °C. By how many degrees did its temperature rise?
answer box°C
40 °C
Hint: Subtract: 58 − 18.