Scientific Method Action

Overview

In this lesson (15 of 20) students practise the steps of the scientific method by planning and running a simple, safe experiment. They focus on making an investigation reproducible by identifying variables, stating assumptions, and recording measurements clearly.

Learning intentions

Students will:

• develop an investigable question and a testable hypothesis about a simple phenomenon
• identify variables (independent, dependent, controlled) and state key assumptions
• plan a reproducible method, including safe risk management
• collect data, summarise results, and justify a conclusion using evidence

Success criteria

Students can:

• write a hypothesis that predicts what will change when one variable changes
• label independent, dependent and controlled variables in their plan
• follow a procedure with consistent measurements and record data in a table
• explain whether evidence supports the hypothesis, and note at least one possible source of error

Curriculum links

• AC9S8I01 — develop investigable questions, reasoned predictions and hypotheses to explore scientific models, identify patterns and test relationships
• AC9S8I02 — plan and conduct reproducible investigations, identifying variables and assumptions and managing risks ethically
• AC9S8I06 — analyse methods, conclusions and claims by identifying possible sources of error, assumptions and unanswered questions

Lesson structure (30 minutes)

1. 0–4 min · Hook: Question vs hypothesis. Teacher shows two example statements on the board: one correlational (“When it’s sunny, plants grow more”) and one causal (“If sunlight increases, plant growth increases”). Students decide which is a testable causal hypothesis and why.

2. 4–10 min · Setup: Choose an experiment. Teacher introduces a short, classroom-safe investigation: “How does water temperature affect how fast sugar dissolves?” Students turn the prompt into an investigable question and write a hypothesis (e.g., “If the water temperature increases, then sugar will dissolve faster”). Note: Temperature of water is the independent variable; time to dissolve is the dependent variable; all other conditions must be controlled.

3. 10–15 min · Plan: Variables, assumptions, method. Teacher guides students to fill a quick planning frame:

• Independent variable: water temperature (choose two or three levels, e.g., cold, room, warm)
• Dependent variable: time taken for sugar to dissolve (start/stop rule)
• Controlled variables: same amount of sugar, same volume of water, same container type/size, same stirring method and duration, same observation criteria Students state at least one assumption (e.g., “stirring speed is consistent” or “the water volume is measured accurately”). Teacher checks for clarity and reproducibility.

4. 15–24 min · Conduct: Record consistent data. Teacher demonstrates the procedure briefly, emphasising safety and consistency. Students perform the test at each temperature level, with a timing rule (e.g., “time from when sugar is added to when no visible crystals remain”). Students record data in a table: temperature level, trials (aim for 2 if time allows), and times. Teacher circulates and corrects technique if needed.

5. 24–28 min · Analyse: Conclusion from evidence. Teacher prompts: “What pattern do you see? Does it match your hypothesis?” Students calculate a simple average time for each temperature level and write a short conclusion statement supported by data.

6. 28–30 min · Exit reflection: Errors and improvements. Students identify one possible source of error (e.g., inconsistent stirring, subjective judgement of “dissolved”, temperature not staying stable) and suggest one improvement for a more reliable result.

Resources

• Sugar, measuring spoons/cups, water
• Containers (same size for each trial), stirring spoons
• Thermometer (or temperature-labelled water sources prepared by teacher)
• Stopwatch/timer or phone timers
• Data table printable (temperature level, trial times, average)
• Safety glasses (if available) and paper towels
• Whiteboard/markers for shared hypothesis and variable planning

Assessment

• Observation during variable identification and planning: correct identification of independent, dependent and controlled variables
• Review of data table: consistent recording and adherence to the timing rule
• Exit reflection: evidence-based conclusion and at least one credible source of error/improvement

Differentiation

• Support: provide sentence starters for hypothesis and conclusion (“If ___ then ___ because…”; “The data show that…”)
• Scaffold: offer a pre-filled controlled variables list to choose from, then ask students to add what’s missing
• Extension (for students who finish early): ask them to propose a third temperature level and predict expected results, or to justify which controlled variable most affects fairness
• One-student pacing: teacher can reduce the number of trials to fit time while keeping the same method for each condition; ensure enough time to record and average results