Estimated time: 50 minutes | Difficulty: Medium | Ref: KS2-WS-1
Learning objective: Plan and conduct investigation into light behaviour
Use the pathway to build a clear mental model. Open each node and answer the check question.
Every investigation starts with a question. For light investigations, this might be: "How does the distance between a light source and an object affect shadow size?" or "Which materials are the best reflectors?"
Check: What makes a good scientific question? (Hint: It should be testable and measurable.)
Identify three types of variables: the independent variable (what you change), the dependent variable (what you measure), and control variables (what you keep the same). A fair test changes only one variable at a time.
Check: If investigating how distance affects shadow size, which variable would you change, and which would you measure?
Take accurate measurements using appropriate equipment (rulers, light meters, protractors). Record your results in a table. Repeat measurements to improve reliability and calculate averages.
Check: Why is it important to repeat measurements and calculate averages?
Look for patterns in your data. Create graphs if helpful. Write a conclusion that answers your original question and explains whether your results supported your prediction. Identify any sources of error or improvements.
Check: How do you know if your results are reliable enough to draw a conclusion?
A light investigation is a scientific enquiry where you plan and carry out experiments to test ideas about how light behaves. You might investigate how light travels, how shadows form, how mirrors reflect light, or how we see objects. The key is using the scientific method to gather reliable evidence.
Good investigations start with careful planning:
Every fair test involves three types of variables:
To make your investigation reliable:
Learning to plan and conduct investigations is a fundamental science skill. Scientists use these same methods to discover new knowledge about the universe. Whether studying how light travels through space or developing new solar panel technology, the scientific method is how we turn questions into reliable answers.
Question: How does the distance between a torch and an object affect shadow size?
Method: Place a cardboard shape 30cm from a screen. Shine a torch from different distances (10cm, 20cm, 30cm, 40cm, 50cm from the object). Measure shadow height each time. Repeat 3 times and calculate averages.
Variables: Independent = torch distance; Dependent = shadow size; Controls = same torch, same object, same screen position.
Question: Which colour surface reflects the most light?
Method: Use a light sensor (or phone app) to measure light reflected from different coloured papers (white, yellow, red, blue, black) when shone with the same torch from the same distance. This type of investigation is used by British road safety engineers when designing hi-vis clothing and road markings.
Variables: Independent = paper colour; Dependent = light sensor reading; Controls = same torch, same distance, same angle.
Question: Does the angle of incidence always equal the angle of reflection?
Method: Place a mirror on paper and draw a normal line. Shine a ray box at different angles (10°, 20°, 30°, 40°, 50°) to the normal. Use a protractor to measure the reflection angle each time. The Cavendish Laboratory in Cambridge used similar techniques when developing optical instruments.
Variables: Independent = angle of incidence; Dependent = angle of reflection; Controls = same mirror, same ray box brightness.
In the 1660s, Isaac Newton conducted famous light investigations at Cambridge University. He used prisms to split white light into a spectrum of colours, then used a second prism to recombine them. His method was scientific: he made predictions, tested them systematically, recorded results, and drew conclusions. This led to our understanding that white light contains all the colours of the rainbow—a discovery still taught in British schools today!
Answer all questions, then check your answers. Your quiz result is saved on this device.
Wrong: Moving the torch closer AND using a brighter torch at the same time. Right: Only change one variable (torch distance) while keeping everything else the same. If you change two things, you won't know which one caused the change in your results!
Wrong: Taking only one measurement at each distance. Right: Take at least 3 measurements and calculate the mean. Single measurements might be errors. If one of your readings is very different from the others (anomalous), you can identify it and investigate why.
Wrong: Saying "I measured the distance" when you mean "I changed the distance." Right: The independent variable is what you deliberately change. The dependent variable is what you measure to see the effect. Remember: the dependent variable "depends" on what you do to the independent variable.
Wrong: "I think light always travels in straight lines because my teacher said so." Right: "My results show that light travels in straight lines because the shadow I measured was the same shape as the object, and blocking the light path stopped the shadow forming." Always use YOUR data to support your conclusion.