Science / Year 6 / Electricity / 5.10
Estimated time: 50 minutes | Difficulty: Medium | Ref: KS2-WS-1
Learning objective: Design and conduct investigation into circuit variables
Use the pathway to build a clear mental model. Open each node and answer the check question.
Start with a scientific question you can test, such as "How does the number of bulbs affect brightness?" Then make a prediction (hypothesis) based on your knowledge of circuits.
Check: What would you predict happens to brightness when you add more bulbs in series?
Identify three types of variables: Independent variable (what you change), Dependent variable (what you measure), and Control variables (what you keep the same for a fair test).
Check: If testing wire length, what would be your independent and dependent variables?
Build your circuit and take measurements carefully. Repeat each test at least three times to ensure reliability. Record results in a clear table as you go.
Check: Why is it important to repeat measurements?
Look for patterns in your results. Calculate averages if you repeated tests. Draw a conclusion that answers your original question. Was your prediction correct? If not, explain why.
Check: What should you do if your results don't match your prediction?
A scientific investigation is a systematic way to answer questions about the world. In electricity, we can investigate how changing different parts of a circuit affects how it works.
Every good investigation needs a clear structure:
For a fair test, you must understand and control variables:
| Variable Type | What it means | Example |
|---|---|---|
| Independent | What you deliberately change | Number of batteries |
| Dependent | What you measure/observe | Bulb brightness |
| Control | What you keep the same | Same bulb, same wires, same circuit type |
To make your results reliable (trustworthy), you should:
Learning to investigate scientifically is a skill you'll use throughout your life. It teaches you to ask good questions, test ideas fairly, and draw conclusions from evidence - essential skills for any scientist!
Question: How does the number of batteries affect bulb brightness?
Independent variable: Number of batteries (1, 2, 3)
Dependent variable: Brightness of the bulb
Control variables: Same bulb, same wires, same type of batteries
Expected result: More batteries = brighter bulb (more voltage pushes more current)
Question: Which materials conduct electricity best?
Independent variable: Type of material tested
Dependent variable: Whether the bulb lights (yes/no) or brightness
Control variables: Same circuit, same battery, same bulb, same length of material
Method: Create a circuit with a gap. Test different materials (metal spoon, plastic ruler, coin, wood, pencil lead) by placing them in the gap.
Question: Are bulbs brighter in series or parallel?
Independent variable: Circuit type (series or parallel)
Dependent variable: Brightness of each bulb
Control variables: Same batteries, same bulbs, same wires
Method: Build two circuits with identical bulbs - one series, one parallel. Compare brightness and record observations.
Question: Does wire length affect how a circuit works?
Independent variable: Length of wire (10cm, 50cm, 100cm)
Dependent variable: Brightness of the bulb
Control variables: Same battery, same bulb, same type of wire
Expected result: Longer wires may slightly reduce brightness due to increased resistance (harder to observe at low voltages).
Answer all questions, then check your answers. Your quiz result is saved on this device.
The independent variable is what YOU change on purpose. The dependent variable is what changes as a result (it "depends" on what you did). A helpful tip: the dependent variable is usually what you're measuring.
For a fair test, you must only change ONE thing at a time. If you change both the number of batteries AND the type of bulb, you won't know which caused your results. Keep everything else the same (controlled).
A single measurement could be wrong due to a mistake or unusual circumstance. Repeating your test at least 3 times and calculating an average makes your results much more reliable. Scientists always repeat experiments!
If your results don't match your prediction, don't hide them or change them! Unexpected results are often the most interesting. Record everything accurately and try to explain WHY the results were different from expected.