Science lesson plan · 9th grade (Year 10 in England) · 30 minutes
Identify gases with laboratory tests
Chemical reactions, acids and bases
CCSS NGSS.HS-PS1-2CCSS NGSS.SEP 3England: GCSE Combined Science: Chemical analysis
Objective and success criteria
Students will: Identify gases with laboratory tests.
- 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: What acids make with metals and carbonates
Leads to: Identify metal ions with flame tests and precipitates
Materials: Teacher demo or video, Indicator color chart, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 4 min
- Quick retrieval from earlier learning (What acids make with metals and carbonates). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- Zinc reacts with hydrochloric acid. What are the products? (zinc chloride + water / zinc chloride + hydrogen / zinc chloride + carbon dioxide / zinc sulfate + hydrogen) → zinc chloride + hydrogenPrompt: acid + metal → salt + hydrogen
- Sodium carbonate reacts with sulfuric acid. What are the products? (sodium sulfate + water + carbon dioxide / sodium oxide + carbon dioxide / sodium sulfate + hydrogen / sodium carbonate + water) → sodium sulfate + water + carbon dioxidePrompt: Carbonates fizz with acids. Which gas turns limewater cloudy?
- How could you prove that the gas from magnesium and acid is hydrogen? (it bleaches damp litmus / it turns limewater cloudy / a lighted splint gives a squeaky pop / it relights a glowing splint) → a lighted splint gives a squeaky popPrompt: Hydrogen burns rapidly with oxygen.
Hook · 3 min
- Drop an antacid tablet in water (or show a clip) and ask whether a new substance is being made.
- Share the objective: Identify gases with laboratory tests. Read the success criteria together.
I do: model it · 7 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: Which gas gives this result: bubbled through limewater, it turns it milky?
- Step 1: Carbon dioxide turns limewater milky (cloudy).
- Step 2: So the answer is: carbon dioxide
- Answer: carbon dioxide
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 6 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- Which gas gives this result: a glowing splint relights? (hydrogen / oxygen / carbon dioxide / chlorine) → oxygenPrompt: Each common gas has its own test.
- Hydrogen peroxide decomposes with a catalyst and the gas relights a glowing splint. Which gas is it? (carbon dioxide / oxygen / chlorine / hydrogen) → oxygenPrompt: Hydrogen peroxide is H₂O₂.
You do: independent practice · 7 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 6 questions are on the student sheet below, with answers in the key.
Exit ticket · 3 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- A gas puts out a lighted splint and turns limewater milky. What is it? (carbon dioxide / hydrogen / chlorine / oxygen) → carbon dioxidePrompt: Fire extinguishers sometimes contain this gas.
- Tests for gases: which statement is NOT true? (Chlorine may turn damp blue litmus red before bleaching it. / Hydrogen gives a squeaky pop with a lighted splint. / Oxygen gives a squeaky pop. / Limewater is a solution of calcium hydroxide.) → Oxygen gives a squeaky pop.Prompt: Which gas pops and which relights a splint?
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: What acids make with metals and carbonates.
- Use concrete materials: teacher demo or video.
- 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: Identify metal ions with flame tests and precipitates.
- 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-9.
Free lesson plan from eurekami.com/lesson-plan-builder