General Knowledge · Class 4 · Science and space
The human body
A newborn baby has about 300 bones, but a grown-up has only 206. Where do the missing bones go?
Small test at the end: scroll down to the end of this page for five short questions that check what you have learnt. Tap an answer, then press Check answer. Go to the questions ↓
Jump to: Read first · Try it away from the screen · Check it yourself · Check yourself · For teachers
Read first
5 facts. The questions below make you use them, not just remember them.
- A grown-up has 206 bones. A newborn baby has about 300, and as the child grows, some of them join together.
- The smallest bone in the body is in the ear. It is about the size of a grain of rice.
- The heart is a pump about the size of your fist. At rest, a grown-up's heart beats about 72 times a minute; a child's beats a little faster.
- When you run, your muscles need more oxygen, so you breathe faster and your heart pumps blood faster to carry it.
- The skin is the biggest organ of the body. Inside the body, the biggest organ is the liver.
Offline
Try it away from the screen
Find your pulse on the inside of your wrist with two fingers. Count the beats for 15 seconds and multiply by 4. Then jump on the spot 20 times and count again. What changed?
Make it on paper. Keep it with you. Nothing to upload.
Check it yourself
Facts about the body change as science learns more, so use a recent science book or a doctor's advice. Be careful with health "tips" forwarded on phones: ask "Who wrote this, and are they a doctor?"
Check yourself
Five questions about what this page teaches. Choose an answer and press Check answer, or open "See the answer and why". Nothing is saved or sent: your choices stay on this screen and disappear when you leave or reload the page.
How do you want to answer? You choose, and you can change at any time.
See the answer and why
- A. 106 Not this one. Too few. Your two hands and feet alone have more than 100 bones.
- B. 206 Correct. Yes. A grown-up skeleton has 206 bones.
- C. 300 Not this one. That is about how many a newborn baby has. Some join together as it grows.
- D. 26 Not this one. One foot has 26 bones. The whole body has many more.
See the answer and why
- A. In the ear Correct. Yes. The stirrup bone in the middle ear is the smallest.
- B. In the little finger Not this one. Finger bones are small, but not the smallest.
- C. In the tip of the nose Not this one. The tip of the nose has no bone at all. It is soft cartilage.
- D. In the little toe Not this one. Toe bones are small, but the ear bone is much smaller.
See the answer and why
- A. 72 Not this one. That is one minute. Ten minutes is ten times as many.
- B. 82 Not this one. That adds 10. Ten minutes means multiply by 10.
- C. 720 Correct. Yes. 72 beats a minute for 10 minutes: 72 × 10 = 720.
- D. 7,200 Not this one. That would be 100 minutes. Multiply by 10, not 100.
See the answer and why
- A. A fast heart cools the body down Not this one. Sweating cools the body. The heart speeds up to carry oxygen.
- B. His muscles need more oxygen, so the heart pumps blood faster Correct. Yes. Blood carries oxygen, so the heart speeds up to deliver more.
- C. His heart is tired and has to work harder to rest Not this one. A tired heart does not speed up to rest. It speeds up to deliver oxygen.
- D. His lungs stopped working for a moment during the race Not this one. His lungs worked harder, not less. He breathes faster to take in more air.
See the answer and why
- A. The brain Not this one. The brain is big and important, but much smaller than the skin.
- B. The liver Not this one. The liver is the biggest organ inside the body, but the skin is bigger.
- C. The skin Correct. Yes. The skin covers the whole body and is the biggest organ.
- D. The heart Not this one. The heart is about the size of a fist.
For teachers and grown-upsWhere the facts come from, and how to use this round.
Sources and notes
- Resting heart rate for children aged about 6 to 15 is roughly 70 to 100 beats a minute; adults about 60 to 100.
- Safety: the jumping task is gentle; children with a health condition skip it.