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Grade 3 (age 8-9)

grade 3 Infectious Disease & Prevention

Have you ever sat next to a friend with a cold and then had a runny nose yourself a few days later? An infectious disease is an illness caused by germs too small to see, such as bacteria or viruses, getting into the body, so it passes from a sick person to other people. Germs ride on the droplets from a cough or sneeze, or they wait on door handles and pencils that many hands touch until the next hand picks them up. The picture shows the path germs take, and the button switches it to prevention rules blocking the middle of that path. You will also learn hand washing in 5 steps.

What is an infectious disease?

🦠 What is an infectious disease?
①An illness caused by invisible germs, such as bacteria or viruses, getting into the body
②Germs from a sick person pass to others, so many people can catch it at once
③Colds, flu, and chickenpox are all infectious diseases
④Cutting the path germs travel also slows how far the illness spreads

How do germs travel?

💡 Three paths germs travel
①Droplets: when someone coughs or sneezes, droplets fly out and reach the nose and mouth of people close by
②Contact: touching your eyes, nose, or mouth with a hand that has germs on it
③Air: very tiny particles can float in the air for a long time and carry germs (chickenpox, measles)
④Like the shield in the picture, blocking a path means fewer people catch it

Washing hands the right way

Order of hand washing

Hand washing in 5 steps
🧼 Why 30 seconds?
①A quick rinse with water alone leaves behind germs stuck in the skin's oil
②Soap foam wraps around the oil and lifts germs off the hands
③The gaps between fingers and the spots under nails are easy to miss, so scrub them on purpose
④Counting slowly to 30 while you scrub makes the time easy to keep

Prevention rules

Prevention rules

Four kinds of prevention rules

Summary

The basics of preventing infection
Hand washing + Cough etiquette + Mask = Prevention
All three habits cut the path germs use to cross
Paths germs travel
Droplets + Contact + Air = Routes of spread
Once you know which path germs take, you can see how to block it
🎯 Key points
①Infectious diseases happen when germs such as bacteria or viruses get into the body
②Germs pass to other people through droplets, contact, and the air
③Washing your hands with soap for 30 seconds or more is the easiest and surest way to prevent them
④Cover coughs with your elbow, and wear a mask in crowded places
⑤Vaccines train the body ahead of time to fight off germs before they arrive

Examples and unit test

Example 1
When germs travel on the droplets that fly out during a cough or sneeze, what is this called?
1
Germs travel by three paths: droplets, contact, and the air.
2
Travelling on the droplets from a cough or sneeze is called droplet transmission.
▸ Droplet transmission
Covering a cough with your elbow keeps droplets from flying far, which cuts down droplet transmission.
Example 2
When you wash with soap, for at least how many seconds should you scrub? Why is it better than rinsing with water alone?
1
The hand washing rule in this unit is to make soap foam and scrub for 30 seconds or more.
2
Soap foam wraps around the oil and germs on your hands and lifts them off, so far more germs wash away than with a quick rinse of water.
▸ 30 seconds or more / soap foam wraps around germs and lifts them off
The 30 seconds only works if you also scrub between the fingers and under the nails.
Unit-test style
Which statement about infectious disease and prevention is correct?
①Infectious diseases are caused by germs such as bacteria or viruses
②A quick rinse with water alone is enough for your hands
③The best way to cover a cough is with your palm
④There is no way to prevent infectious diseases
⑤A mask only needs to cover your mouth
▸ ① Infectious diseases are caused by germs such as bacteria or viruses
1
An infectious disease happens when invisible germs get into the body, and it passes from person to person.
2
Hands need soap and 30 seconds or more (②), a cough covered by the palm spreads again through the hand, so use the elbow (③), hand washing and masks do prevent it (④), and a mask must cover both nose and mouth (⑤).
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