Year 4 Science: Pitch and the object that makes the sound
Part of the Year 4 Science sound chapter. Chapter overview · whole chapter on one page
Pitch and the object that makes the sound
Pitch is how high or low a sound is. A high sound has a high pitch, and a low sound has a low pitch.
Pitch depends on how fast the object vibrates. Fast vibrations give a high pitch. Slow vibrations give a low pitch. The features of the object decide how fast it vibrates. A ruler with a long part over the edge vibrates slowly, so its pitch is low. A thin string pulled tight vibrates fast, so its pitch is high.
The table shows the three rulers from the picture, with the length hanging over the edge.
| Ruler | Length hanging over the edge | Pitch of the sound |
|---|---|---|
| short overhang | 5 cm | high |
| medium overhang | 10 cm | middle |
| long overhang | 15 cm | low |
Key ideas
- Pitch is how high or low a sound is.
- Fast vibrations make a high pitch; slow vibrations make a low pitch.
- A longer part that vibrates makes a lower pitch.
- A thin string, pulled tight, makes a higher pitch than a thick string pulled loose.
Method. Find the high pitch.
- Read the table. The short overhang gives a high pitch.short overhang
- Name it. So the short overhang gives the highest pitch.short overhang
- Write the answer. short overhang
Check. Less overhang vibrates faster, so the pitch is higher. ✓
Method. Compare the two strings.
- Read the pattern. A thin string pulled tight makes a high pitch.high pitch
- Compare. A thick string pulled loose makes a low pitch, so the thin tight string is higher.higher
- Write the answer. higher
Check. Thin and tight strings vibrate faster. ✓
Method. Subtract the shortest from the longest.
- Read the lengths. The long overhang is 15 cm, and the short overhang is 5 cm.15 and 5
- Subtract. 15 minus 5 is 10.15 - 5 = 10
- Write the answer. 10
Check. Check: 5 plus 10 makes 15. ✓
Watch out. Subtract the smaller length from the larger one.
Watch out
Watch out: a high pitch is not the same as a loud sound. Pitch is about how high or low; loudness is about how big the vibration is.
Try it at home or school (with a grown-up). Hold a ruler over the edge of a table, with a grown-up. Make it vibrate with a short overhang, and then with a long overhang. Say which one has the higher pitch. Keep your fingers away from the moving end.
Exam tip
Grown-up tip. Ask: “Which overhang is longer? Which pitch is higher?” Let your child predict the pattern before testing it.
Exercise 8C Pitch and the object that makes the sound
Method. Read the key idea in section 8.3.
- Read the key idea. Pitch is how high or low a sound is.pitch
- Write the answer. pitch
Check. Pitch is about high or low, not loud or quiet. ✓
Method. Read the table.
- Read the pitch column. The long overhang has a low pitch.low pitch
- Write the answer. long overhang
Check. A long part vibrates slowly. ✓
Method. Read the table.
- Read the pitch column. The short overhang has a high pitch.high pitch
- Write the answer. short overhang
Check. A short part vibrates fast. ✓
Method. Read the strings in section 8.3.
- Read the string row. The thin string pulled tight gives a high pitch.high pitch
- Write the answer. higher
Check. Thin and tight strings vibrate fast. ✓
Method. Read the strings in section 8.3.
- Read the string row. The thick string pulled loose gives a low pitch.low pitch
- Write the answer. lower
Check. Thick and loose strings vibrate slowly. ✓
Method. Read the medium row.
- Read the row. The medium overhang row says 10 cm.10 cm
- Write the answer. 10
Check. Ten centimetres is between 5 and 15. ✓
Method. Subtract the shortest from the longest.
- Read the lengths. The longest is 15 cm, and the shortest is 5 cm.15 and 5
- Subtract. 15 minus 5 is 10.10
- Write the answer. 10
Check. Check: 5 plus 10 is 15. ✓
Method. Read the key idea in section 8.3.
- Read the key idea. Fast vibrations give a high pitch.high pitch
- Write the answer. higher
Check. Fast vibrations are higher. ✓
Method. Read the bottle pattern in section 8.3.
- Read the pattern. A bottle with a lot of water has less air to vibrate, so it has a low pitch.low pitch
- Compare. So a bottle with a lot of water has a lower pitch.lower
- Write the answer. lower
Check. Less air in the bottle means slower vibration. ✓
Method. Read the table in section 8.3.
- Read the long row. The long overhang gives a low pitch.low pitch
- Decide. So Ruby is not right.no
- Write the answer. no
Check. A longer part vibrates more slowly. ✓
Method. Use the pattern in section 8.3.
- Think about the pattern. A longer part vibrates more slowly.more slowly
- Make the prediction. So the long overhang should have the lowest pitch.lowest pitch
- Write the answer. Accept any prediction that the long overhang gives the lowest pitch, because it vibrates more slowly.
Check. Test it with a grown-up, and say which pitch is higher. ✓
Method. Think about the vibrations.
- Think about the string. A thin string pulled tight can vibrate quickly.vibrate quickly
- Write the reason. Fast vibrations make a high pitch.high pitch
- Write the answer. Accept any sentence that says a thin string pulled tight vibrates faster, so it has a higher pitch.
Check. The pattern links the object to the pitch. ✓