---
title: "The Immune System"
description: "Know that the immune system helps protect the body from illness: skin blocks many germs, white blood cells help fight bacteria and viruses, and vaccines prepare an immune response to specific germs"
canonical: https://lightmysky.com/learn/science/the-immune-system-mt_4JpMXUIxeD
source: https://lightmysky.com/learn/science/the-immune-system-mt_4JpMXUIxeD.md
retrieved: 2026-11-12
---

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# The Immune System

Know that the immune system helps protect the body from illness: skin blocks many germs, white blood cells help fight bacteria and viruses, and vaccines prepare an immune response to specific germs

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 unbroken skin as a first barrier against germs and explain how cuts can leave gaps in that barrier
- Explain that white blood cells help find and fight bacteria and viruses, including unfamiliar germs, but do not stop every infection
- Explain that vaccines prepare an immune response to specific germs; examples use weakened or inactive germs, germ parts, or instructions for making a harmless germ part

## Lesson: How Your Body Fights Germs

Your body is made of cells. The immune system helps defend your body against germs that can cause illness. Bacteria are living cells. Viruses are particles that need living cells to multiply.

Unbroken skin is a first line of defence. It blocks many germs. A cut leaves a gap in this barrier. Germs can also enter through your nose or mouth.

White blood cells help find and fight germs inside the body. Some swallow bacteria; others attack cells infected by viruses. They can respond to unfamiliar germs without a vaccine. You can still become ill while they fight. Injury or infection can cause inflammation, making a scrape red or sore. Redness alone does not prove that germs entered.

*(drawing: Vaccination can build immune memory. On meeting the matching germ later, the body may respond faster.)*

Vaccines prepare an immune response to a specific germ. Some use weakened or inactive germs. Some use germ parts or instructions for making a harmless germ part. This training can build immune memory, so the body may respond faster if it meets the matching germ later. Vaccines lower the risk of illness, but do not give complete protection or replace other defences.

**Recap.** Skin blocks many germs. White blood cells fight germs inside the body. Vaccines prepare a response to specific germs, but protection is not complete.

*Original lesson, questions and flashcards written for this dataset.*

## 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

- [Immunity & Vaccines](https://lightmysky.com/learn/science/immunity-and-vaccines-mt_LkOMijDvL7)