Variable Experiment

Overview

In this lesson (5 of 10) students investigate how scientific investigations test ideas by changing one variable at a time and observing what happens. They will run a short investigation that links independent, dependent and controlled variables to evidence.

Learning intentions

• Students will be able to explain the difference between independent, dependent and controlled variables.
• Students will predict what will happen when they change the independent variable.
• Students will conduct a fair test by keeping controlled variables the same.
• Students will record observations and conclude whether their results match their predictions.

Success criteria

• I can identify the independent, dependent and controlled variables in an investigation.
• I can state a prediction using clear cause-and-effect language.
• I can run a fair test by changing only the independent variable.
• I can use my data to decide whether my conclusion supports my prediction.

Curriculum links

• Science understanding: investigating and comparing the effect of variables in practical investigations
• Science inquiry skills: planning investigations, using appropriate materials, recording observations and drawing conclusions from evidence
• Scientific communication: using tables/labels to record and explain findings clearly
• Evidence-based reasoning: linking observations to conclusions

Lesson structure (60 minutes)

1. 0–5 min | Welcome and focus

• Students recap what makes a test fair from previous lessons in the unit. Display a simple “change one thing, measure another, keep the rest” reminder and connect it to today’s activity.

2. 5–15 min | Mini-lesson: variables in kid-friendly terms

• Explain and model:
• Independent variable = what the scientist changes.
• Dependent variable = what the scientist measures/observes.
• Controlled variables = what the scientist keeps the same.
• Use a quick class example (e.g., “Changing light distance changes how fast a plant grows” or “Changing ramp height changes how far a toy rolls”). Ask students to identify the variables using think-pair-share.

3. 15–25 min | Predict and plan

• Students receive an investigation brief (Teacher-led choice of one investigation setup suitable for the equipment available).
• As a whole class, co-create a prediction sentence frame:
• “If we change ___ (independent variable), then ___ (dependent variable) will likely ___ because…”
• Students complete a variables table for their group: independent, dependent and at least two controlled variables.

4. 25–45 min | Hands-on investigation (fair testing)

• In groups of 4–5 (25 students total), students conduct the investigation.
• Teacher circulates with a checklist: “Did you change only the independent variable?” “Are you measuring the dependent variable the same way each time?” “Are controlled variables consistent?”
• Students repeat measurements where possible (e.g., two or three trials) and record results promptly.

5. 45–52 min | Data check and clean-up

• Students pause to confirm their data is complete: units, consistent measurements, and at least one comparison between trials.
• Teacher prompts correction immediately (e.g., “Your dependent variable should be the measurement you chose—check your table headings.”).
• Students tidy equipment and prepare for sharing results.

6. 52–58 min | Conclusion writing

• Students write a short conclusion using evidence:
• “Our results show that ___ changed/ did not change when we changed ___.”
• “This supports/does not support our prediction because…”
• Encourage use of observations and numbers rather than opinions.

7. 58–60 min | Exit ticket: variable accuracy

• Each student completes a brief exit ticket:
• Identify independent and dependent variables from a short scenario (not their own setup).
• Write one controlled variable that should be kept the same.

Resources

• Investigation brief cards (one per group) with a clear question and variables prompt
• Group data table worksheets (headings: independent variable, dependent variable, controlled variables, trial results)
• Timers, rulers/measuring tapes, stopwatches (as appropriate to the chosen investigation)
• Materials for the experiment (choose based on availability):
• Ramp and balls/toys OR
• Paper cups and water OR
• Light source and distance markers OR
• Rubber bands and objects for tension/stretch tests
• Safety equipment (if needed): goggles, aprons or lab mats
• Anchor chart: “Fair test checklist”
• Coloured pencils/markers for recording
• Teacher checklist for circulating and quick feedback

Assessment

• Formative: teacher observation during experimentation using a fair-test checklist (variable identification and measurement consistency).
• Formative: students’ predictions and completed variables table (accuracy of independent/dependent/controlled variables).
• Summative-in-miniature: exit ticket scoring for correct identification of variables and one appropriate controlled variable.

Differentiation

• Support:
• Provide sentence starters for predictions and conclusions.
• Offer a partially completed variables table for students who need reduced cognitive load.
• Pair learners strategically and assign specific roles (materials manager, recorder, measurement checker).
• Extension:
• Ask: “What would happen if we changed a different controlled variable?” (They explain why it is not part of this test.)
• Encourage more than one dependent measure if appropriate (e.g., two measurement types).
• EAL:
• Use visual supports (icons for “change”, “measure”, “keep the same”) and allow oral rehearsal before writing.
• Provide word banks for variables and cause-and-effect language.
• SEN:
• Chunk the task into timed sections (plan → predict → trial 1 → trial 2 → record → conclude).
• Reduce writing volume while ensuring accurate variable identification and at least one set of measurements.