Gases in Action

Overview

In this lesson (Lesson 2 of 8), students conduct a safe, repeatable investigation using vinegar and baking soda to produce gas. They connect their observations to the particle model by explaining that gases take up space and have mass, using evidence from balloon weighing.

Learning intentions

WALT:

• model solids, liquids and gases using particles arranged and moving differently
• plan and conduct a fair, repeatable investigation to test gas production from vinegar and baking soda
• record measurements with reasonable precision and use evidence to explain what the gas is doing (taking up space and adding mass)

Success criteria

• I can explain how the particle movement/arrangement helps us understand why a gas forms and changes how objects behave.
• I can conduct a fair test by keeping key variables the same and measuring what matters.
• I can record data in a table (including masses) and use it as evidence for my conclusion.
• I can describe at least one source of error and how it could affect results.

Curriculum links

• AC9S5U04: explaining observable properties of solids, liquids and gases by modelling the motion and arrangement of particles
• AC9S5I02: planning and conducting repeatable investigations, including variables, risk/safety and permissions where relevant
• AC9S5I03: using equipment to observe, measure and record data with reasonable precision
• AC9S5I04: constructing and using representations (tables/graphs/models) to organise and process information
• AC9S5I05: comparing methods/findings with those of others, recognising possible sources of error, and drawing reasoned conclusions

Lesson structure (80 minutes)

1. 0–8 min · Hook (Think–Pair–Share). Teacher demonstrates a balloon inflating from a gas-producing setup (using materials already prepared) and asks what might be inside the balloon and what it’s doing to the balloon. Students think-pair-share and list “I notice / I wonder” statements.

2. 8–18 min · Direct teach: particle model + outcomes. Teacher revisits the particle model: in gases particles are far apart and move freely, which helps explain how gases spread, press, and fill containers. Students complete a quick “Gas particles” role-play sketch or mini-diagram in notebooks (one sentence: “Because…, gases…”).

3. 18–30 min · Investigation planning (fair test focus). Teacher guides students to choose variables for the vinegar + baking soda reaction and agree what will be measured/controlled (e.g., vinegar volume, number of tablets/grams of baking soda, container type, start timing, temperature assumptions). Students draft the method steps in a short checklist: variables to change, measure and control; plus safety reminders.

4. 30–48 min · Experiment setup and gas production. Teacher models the safe setup: students place vinegar into a container, add measured baking soda, then immediately connect/secure a balloon or sealed collection system to capture gas. Students run the reaction, start timing at the same point each trial, and observe balloon size and any changes (e.g., foam/bubbling).

5. 48–60 min · Weighing for mass evidence. Teacher demonstrates how to weigh an empty balloon (or balloon before filling) and a filled balloon, emphasising careful handling and consistent timing (e.g., after 2 minutes). Students measure and record masses for at least one trial, using a table. Teacher circulates to check units and reading of scales.

6. 60–70 min · Data processing + explanation. Teacher asks students to calculate the mass change (filled minus empty) and write a short claim-evidence-reasoning statement linking results to “gases have mass” and “gases take up space.” Students share within groups and add one improvement idea for a more reliable result.

7. 70–78 min · Compare findings + sources of error. Teacher leads a brief class discussion comparing results across groups and naming common error sources (e.g., balloon leakage, inconsistent timing, scale not tared correctly, different initial balloon mass, spillage). Students answer: “Our result may be different because…” and choose one improvement.

8. 78–80 min · Exit ticket (quick formative check). Students complete two prompts on a slip:

• “Gases take up space because…”
• “The evidence that gas has mass is…”

Resources

• vinegar (measured for groups), baking soda (pre-portioned or measured), balloons (same size), containers/cups
• measuring cylinders or syringes, teaspoons/spoons and/or digital scales for baking soda measurement
• kitchen/bench balance scales (or classroom digital scales), taring supplies, gloves and safety glasses
• timer/phones (teacher-approved) or classroom timers
• data recording sheets with a class table template (empty mass, filled mass, mass change, notes)
• paper towels, wipes, bin for waste
• student notebooks and pencils
• labels for groups and materials

Assessment

• Teacher observation during planning and setup: check that variables are controlled and safety procedures are followed.
• Review of group tables for accurate measurement recording (units, consistent timing, mass calculations).
• Exit ticket: use to confirm understanding of gases taking up space and having mass, and whether the particle model explanation is being used.

Differentiation

• Support:
• Provide a partially completed method checklist and a sentence starter for claim-evidence-reasoning (e.g., “My evidence shows…, which means…”).
• Pair students strategically and assign clear roles (measurer, recorder, materials manager, safety officer).
• EAL / language support:
• Word bank on the board: gas, mass, empty, filled, balloon, measure, evidence, fair test, control.
• Allow oral responses to the exit ticket with a teacher quick note, then record the key idea.
• Precision support:
• Model how to read scales and how to record to the nearest appropriate unit; show an example filled-in table.
• Extension (advanced learners):
• Ask groups to suggest and test a second fair variable (e.g., different vinegar volume while keeping baking soda mass constant) and predict how the mass change might differ before running it.
• Challenge: identify which steps most affect reliability (leakage, timing, volume accuracy) and propose a method to reduce that error.

References to prior learning

Students have already begun classifying substances and discussing observable properties; today they use a chemical reaction as evidence to strengthen the gas particle model.