Science lesson plan · 2nd grade (Year 3 in England) · 45 minutes
Heating and cooling: can the change be undone?
States of matter
CCSS NGSS.2-PS1-4England: KS1 Y2 Uses of everyday materialsEngland: KS2 Y5 Properties and changes of materials
Objective and success criteria
Students will: Heating and cooling: can the change be undone?.
- 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: Melting, freezing, evaporating and condensing
Leads to: What happens when we heat it?; What happens when we cool it?
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 (Melting, freezing, evaporating and condensing). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Which change of state is this: melted wax going hard again? (melting / freezing / evaporating / condensing) → freezingPrompt: What state does it start in, and what state does it end in?
- What is the name for a change from liquid to gas? (evaporating (or boiling) / condensing / freezing / melting) → evaporating (or boiling)Prompt: Heating makes solids melt and liquids evaporate.
- Changes of state: which statement is true? (Heating can make a solid melt. / Water only evaporates when it boils. / The water on the outside of a cold can leaks through the metal. / Melting makes a substance lose mass.) → Heating can make a solid melt.Prompt: Where does the water on a cold can come from?
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: Heating and cooling: can the change be undone?. 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: Can this change be undone: frying an egg?
- Step 1: Cooking and burning make new materials that cannot be turned back.
- Step 2: So the answer is: cannot change back
- Answer: cannot change back
- 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.
- Can this change be undone: chocolate melting in a warm hand? (can change back / cannot change back) → can change backPrompt: Could you get the starting material back by warming it or cooling it?
- Three of these changes CANNOT be undone. Which one is different? (popping popcorn / burning a log on a fire / water freezing into ice cubes / toasting bread) → water freezing into ice cubesPrompt: Think about melting and freezing versus cooking and burning.
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.
- Three of these changes CAN be undone. Which one is different? (candle wax melting / chocolate melting in a warm hand / butter softening in a warm kitchen / baking a cake) → baking a cakePrompt: Think about melting and freezing versus cooking and burning.
- Can you turn a fried egg back into a raw egg by putting it in the fridge? (Yes, cooling always undoes heating. / Yes, if you wait a day. / No, cooking made a change that cannot be undone. / Yes, but only for brown eggs.) → No, cooking made a change that cannot be undone.Prompt: Is a cooked egg white still see-through and runny?
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: Melting, freezing, evaporating and condensing.
- 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: What happens when we heat it?; What happens when we cool it?.
- 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-2.
Free lesson plan from eurekami.com/lesson-plan-builder