---
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: 2026-10-19
---

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# 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 hypothesis in the form 'I predict that [IV] will affect [DV] because...' 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

A hypothesis is a prediction with a reason. Scientists write it like this: 'I predict that [the thing I change] will affect [the thing I measure], because...' The 'because' part explains the science behind your idea, not just what you think will happen.

**Example.** Priya wonders whether water temperature affects how fast sugar dissolves. Her hypothesis: 'I predict that increasing the water temperature will speed up how quickly sugar dissolves, because heat makes the water particles move faster and bump into the sugar more often.'

*(drawing: The hotter the water, the less time the sugar took to dissolve. That supports Priya's hypothesis.)*

Before testing, plan three things. The independent variable is what you deliberately change (water temperature). The dependent variable is what you measure (time to dissolve). The control variables are everything else you keep exactly the same, for example the amount of sugar, the amount of water, and how much you stir. Repeat each reading at least three times so one odd result doesn't spoil your data.

**Tip.** Always think about safety before you start. Hot water can scald, so list it as a hazard and write a control measure next to it, such as using oven gloves or asking an adult to pour it.

**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.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Controlling variables](https://lightmysky.com/learn/science/controlling-variables-mt_ArVBEpMAPk)
- [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)