You’re going to be a science explorer!
Fantastic! You’re learning key words about how the human body works.
Like your heart, your brain never stops working. Your brain gets messages from your sense organs, your eyes, ears, tongue, skin and nose. Your brain uses that information when you think, talk, write and move. This helps you talk, write, do mathematics, play games and more. You need your brain for everything you do!

If you make your brain work hard it gets better. Scientists know that, even when you get things wrong, if you keep trying your brain will improve.

1. Can you feel your heart beating?
2. Have you felt your heart beat faster after you have been running or playing?
You will need: a stopwatch
Marcus and Zara are investigating how their hearts speed up when they exercise.
Observation: Your heart rate went up from 65 beats per minute to 85 beats per minute.
The bar chart shows how Zara’s heart rate changed when she exercised and then rested. The data are summarised in this table:
| Time we measured heart rate | Heart rate (beats per minute) |
|---|---|
| At rest | 65 |
| After 1 minute of exercise | 85 |
| 2 minutes after the exercise | 65 |

Answer these questions.
Now use a watch to take the pulse of a friend at rest, after 1 minute’s exercise and again two minutes later.
Do you see a similar pattern of an increase in heart rate followed by a return to the resting heart rate?
In your chest are your two lungs. When you breathe in, your chest gets bigger and sucks air into your lungs. Oxygen in the air then moves into your blood.
If you exercise your body will need more oxygen. Your lungs will take more breaths each minute so that there is more oxygen in your blood. Children take more breaths than an adult because their lungs are smaller.

You will need: a stopwatch
Predict how many breaths you will take in one minute. Predict the number at rest and then predict the number after exercise.
While you sit at rest, count the times you breathe in during one minute. This is your breathing rate at rest.
Then after one minute of gentle exercise, count your breaths again for one minute. This is your breathing rate after exercise.
Example observations:
✔ “That’s 26 breaths in one minute.”
✔ “I predict it may be about 35 breaths in one minute.”
✔ “After one minute of exercise I will count how many times I breathe in for one minute.”
| My prediction of breaths in one minute at rest | My prediction of breaths in one minute after exercise | Number of breaths in one minute at rest | Number of breaths in one minute after exercise |
|---|---|---|---|
Were your predictions right?
Sofia and Marcus tested the breaths per minute of two teachers. They recorded the results in this table.
| Person | Age | Prediction At rest | Breathing Rate at Rest | Prediction after exercise | Breathing Rate after Exercise |
|---|---|---|---|---|---|
| Sofia | 11 | 20 | 26 | 40 | 50 |
| Marcus | 11 | 35 | 27 | 45 | 48 |
| Mr. Zan | 31 | 30 | 23 | 40 | 41 |
| Mrs. Bell | 29 | 25 | 24 | 35 | 39 |
1. Why does the breathing rate per minute always increase after exercise?
2. Whose breathing rate per minute increased most?
3. Why was the breathing rate per minute of the adults lower than that of the children?
When you eat, your food goes to your stomach and intestines. Your intestines absorb important nutrients from your food. Nutrients are things in your food that help your body to grow and work well. Nutrients help to keep you healthy.
The food then passes out of your intestines and into the toilet as waste.

4. What organ makes the blood travel around your body?
Like your heart, your brain never stops working. Your brain gets messages from your sense organs, your eyes, ears, tongue, skin and nose. Your brain uses that information when you think, talk, write and move. This helps you talk, write, do mathematics, play games and more. You need your brain for everything you do!

If you make your brain work hard it gets better. Scientists know that, even when you get things wrong, if you keep trying your brain will improve.
5. Can you remember a time when you had to think very hard?
6. Do you know a game that makes your brain work hard?
