Science lesson plan · 7th grade (Year 8 in England) · 45 minutes
Melting and boiling points
States of matter
CCSS NGSS.MS-PS1-4England: KS3 Chemistry: The particulate nature of matterEngland: KS4 Combined Science: Particle model of matter
Objective and success criteria
Students will: Melting and boiling points.
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Temperatures of water changing state; The particle model
Leads to: Specific heat capacity and latent heat
Materials: Ice, water and a kettle (teacher demo), Particle diagrams, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Temperatures of water changing state; The particle model). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Which state is described: particles close together in a random arrangement? (solid / liquid / gas) → liquidPrompt: How close are the particles, and how do they move?
- Water in a pan starts at 21 °C. By how many degrees must it warm up to reach its boiling point? → 79 °CPrompt: At what temperature does water boil?
- Which state is described: particles touching but able to slide past each other? (solid / liquid / gas) → liquidPrompt: How close are the particles, and how do they move?
Hook · 5 min
- Show an ice cube melting and a kettle steaming and ask what is the same and what is different.
- Share the objective: Melting and boiling points. Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Nitrogen melts at −210 °C and boils at −196 °C. What state is it in at −218 °C?
- Step 1: −218 < −210
- Step 2: So the answer is: solid
- Answer: solid
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Nitrogen melts at −210 °C and boils at −196 °C. What state is it in at −203 °C? (solid / liquid / gas) → liquidPrompt: Is the temperature below the melting point, between the two, or above the boiling point?
- Ethanol melts at −114 °C and boils at 78 °C. Over how many degrees is it a liquid? → 192 °CPrompt: It is a liquid between its melting point and its boiling point.
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Bromine melts at −7 °C and boils at 59 °C. What state is it in at 26 °C? (solid / liquid / gas) → liquidPrompt: Is the temperature below the melting point, between the two, or above the boiling point?
- Which of these substances is a liquid at room temperature (20 °C)? oxygen: melts −218 °C, boils −183 °C bromine: melts −7 °C, boils 59 °C sulfur: melts 115 °C, boils 445 °C copper: melts 1085 °C, boils 2562 °C (copper / sulfur / bromine / oxygen) → brominePrompt: A liquid at 20 °C melts below 20 °C and boils above 20 °C.
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Temperatures of water changing state.
- Use concrete materials: ice, water and a kettle (teacher demo).
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Move on to: Specific heat capacity and latent heat.
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-7.
Free lesson plan from eurekami.com/lesson-plan-builder