---
title: "The Immune System"
description: "Know that the body has an immune system that protects against illness: the skin acts as a barrier, white blood cells identify and destroy germs (bacteria and viruses), and vaccines train the immune sy"
canonical: https://lightmysky.com/learn/science/the-immune-system-mt_4JpMXUIxeD
source: https://lightmysky.com/learn/science/the-immune-system-mt_4JpMXUIxeD.md
retrieved: 2026-10-19
---

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# The Immune System

Know that the body has an immune system that protects against illness: the skin acts as a barrier, white blood cells identify and destroy germs (bacteria and viruses), and vaccines train the immune system to recognise specific diseases before they cause illness

Subject: Science · Area: The Human Body · Ages 9 to 11
Page: https://lightmysky.com/learn/science/the-immune-system-mt_4JpMXUIxeD

## Ready when they can

- Describe the skin as the body's first line of defence against germs
- Explain that white blood cells detect and fight bacteria and viruses inside the body
- Describe how vaccines work: they contain weakened or inactive germs that train the immune system to recognise the real disease

## Lesson: How Your Body Fights Germs

Germs are tiny living things, like bacteria and viruses, that can make you sick. Your body has its own defence system called the immune system, and it works hard to stop germs before they cause trouble.

The first line of defence is your skin. It covers your whole body like a shield and keeps most germs from getting inside. Germs usually only get in through a cut, scrape, or an opening like your nose or mouth.

**Example.** Mia scrapes her knee on the playground, and some germs slip in through the cut. White blood cells rush to the spot, find the germs, and destroy them before Mia gets sick.

*(drawing: Skin blocks germs first. White blood cells fight germs that get inside. Vaccines train white blood cells ahead of time.)*

**Tip.** A vaccine is like a safe training session for your immune system. It contains a weakened or inactive germ, too weak to make you sick, but strong enough for your white blood cells to learn what it looks like. If the real disease ever shows up, your body already knows how to fight it.

**Recap.** Skin blocks germs first, white blood cells destroy the germs that get inside, and vaccines train your immune system ahead of time.

## Practice

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

## Needs first

- [Cells, Tissues & Organs](https://lightmysky.com/learn/science/cells-tissues-and-organs-mt_C7FNeIDGc6)

## Opens up

- [Healthy Lifestyle Choices](https://lightmysky.com/learn/science/healthy-lifestyle-choices-mt_4k3HGahK2k)
- [Immunity & Vaccines](https://lightmysky.com/learn/science/immunity-and-vaccines-mt_LkOMijDvL7)