Year 7 Science · Unit 3 · Lesson 20
Challenge Worksheet
Learning Goals
Design a mini-experiment
A scientist wants to test: "Does the length of a pendulum affect the time it takes to complete one full swing (the period)?" Plan a complete fair-test investigation below.
| What I will change (independent variable) | |
| What I will keep the same (controlled variables — list at least 3) | |
| What I will measure (dependent variable) and how | |
| My hypothesis (use: "If [IV] is increased, then [DV] will … because …") | |
| Why I will time 10 swings and divide by 10, rather than timing just 1 swing | |
| How I would know if my hypothesis is wrong | |
| One limitation of this experiment and how I could reduce it |
Results table — fill in the column headings and units:
1. The classic pendulum result surprises most students: mass and starting angle do NOT affect the period (for small swings), but string length does. Using ideas from Unit 3 about forces and energy, suggest a scientific reason why a longer string leads to a longer period. Hint: think about the arc the bob must travel and the forces acting on it.
2. A friend says: "Pendulums are just an old-fashioned toy — they have nothing to do with real science." Using at least two connections to Unit 3 concepts (e.g. energy conservation, Newton's Laws, forces, energy forms) and one real-world application, write a response that challenges this claim.
Wrap Up
What was the most surprising connection between forces and energy that you discovered in Unit 3?