--- title: "Controlling variables (age 11+)" description: "Form a testable scientific hypothesis linking an independent variable to a predicted outcome, plan a full investigation identifying independent, dependent, and control variables, sample size, and risk" canonical: https://lightmysky.com/learn/science/controlling-variables-age-11-mt_Ae56umVlTT source: https://lightmysky.com/learn/science/controlling-variables-age-11-mt_Ae56umVlTT.md retrieved: 2026-11-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Controlling variables (age 11+) Form a testable scientific hypothesis linking an independent variable to a predicted outcome, plan a full investigation identifying independent, dependent, and control variables, sample size, and risk assessment Subject: Science · Area: Scientific Inquiry · Ages 11 to 12 Page: https://lightmysky.com/learn/science/controlling-variables-age-11-mt_Ae56umVlTT ## Ready when they can - Writes a testable prediction linking an independent variable to an expected dependent-variable outcome, supported by scientific reasoning - Identifies and labels the independent variable, dependent variable, and at least three control variables - Plans repeat readings and an appropriate sample size, and identifies relevant hazards with control measures ## Lesson: Writing a hypothesis and planning a fair test You have planned fair tests before. A hypothesis is a possible explanation that can be tested. It can lead to a prediction. In this lesson, name the condition you will change, the outcome you expect to measure and a scientific reason for that expectation. You can join these with 'I predict ... because ...', but scientists do not have to use those exact words. **Example.** Priya predicts that sugar will dissolve faster in warmer water. Water particles move faster when warmed, which helps sugar mix into the water. She will change water temperature and measure dissolving time in seconds. She will use the same sugar mass, water volume and stirring method for each trial. *(drawing: Example trial times in seconds. Shorter times in warmer water support the prediction if other relevant conditions stayed the same.)* The independent variable is what you change on purpose: water temperature. The dependent variable is the outcome you measure: dissolving time. Control variables are relevant conditions kept the same. Priya keeps sugar mass, water volume and stirring method fixed. Changing both sugar mass and temperature would make it hard to separate their effects on dissolving time. Sample size counts separate objects, not readings. Several plants at each light level let you compare variation between plants. Repeated height readings of each plant check measurement variation. Explain your planned counts using likely variation and available time. For the sugar test, three fresh trials at each temperature are a starting plan, not a guarantee. Keep unusual results and investigate them. More objects or repeats cannot repair a faulty method. A risk assessment names a hazard, the harm it could cause and a way to reduce the risk. Hot water can scald skin. An adult should handle and pour hot water for this activity. Use suitable containers on a stable, heatproof surface. Never use a finger to test the temperature. Follow your teacher's safety instructions. **Example.** Plan the sample and repeats together. Multiply plants by readings per plant to check the total. With a limit of 20 readings and four readings per plant, five plants fit: 5 × 4 = 20. Divide the reading limit by readings per plant to find the largest sample. Count whole plants only; do not exceed the limit. **Recap.** A strong investigation starts with a hypothesis that has a reason, then a fair test that changes only one thing, repeats its readings, and plans for safety. *This lesson, its questions and its flashcards were written for this dataset.* ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Controlling variables](https://lightmysky.com/learn/science/controlling-variables-mt_ArVBEpMAPk) ## Optional connections - [Planning a task](https://lightmysky.com/learn/learning-to-learn/planning-a-task-mt_QR3vxbN1o4) - [Structured Opinion Writing](https://lightmysky.com/learn/english/structured-opinion-writing-mt_WKxX-b86Vr) ## Opens up - [Testing a New Drug: Controls, Placebo and the Blind Trial](https://lightmysky.com/learn/science/testing-a-new-drug-controls-placebo-and-the-blind-trial-mt_If6qHIrOxT) - [Writing Science Reports](https://lightmysky.com/learn/science/writing-science-reports-mt_ThTbUuNb3p)