Bottle orchestra

Activity overview

Run the activity

1. You’re going to watch a short video. The aim isn't to find right answers, it's to explore ideas and find out what they know.

• Do they know what might happen based on the image?

2. After you've watched the video, lead a discussion with your class:

• Why do the class think the bottles are lined up like this?
• What do they think will happen to each bottle when they're tapped?
• Why do the class think there are different levels of liquid in each bottle?
• How do they think the sound is made?

3. Ask the class to describe what they saw using only one word.

Background science

This video shows how many notes you can make with a few glass bottles and some liquid! When you tap an empty glass bottle the glass vibrates and makes a sound, or note. Adding liquid to each bottle slows the speed of the vibrations of the glass. Slower vibrations lower the pitch, so a bottle full of water has a low pitch and an emptier bottle has a higher pitch. We’ve used coloured liquid to make this really clear, but plain water works just as well.

Watch out for:  

Children often confuse pitch and volume, so it is important to be clear that pitch is about whether the instrument makes a high or low sound. Volume is about how loud or quiet a sound is. This PSTT resource looks at all the common misconceptions linked to sound. This does not need to be corrected during the session; you can pick it up later. 

Take it further

Activities  

If you recreate this activity in the classroom and blow over the mouths of the bottles, rather than tap them, you'll get a completely different result. The bottle with the smallest amount of water, that made a high note when tapped, will make a low note when blown. This is because when you blow over a bottle you're vibrating the air, not the bottle!  

If you have musical instruments in school, give the children opportunities to explore and investigate how the pitch is changed on each instrument. The Ogden Trust offers this Phizzi enquiry for children to explore the pitch and volume of homemade ‘instruments’. 

Watch  

This BBC film explores pitch and shows what sounds would look like if we could see them. There are some useful sound videos featuring Professor Brian Cox here. 

Linked Explorify activities- our recommendations:  

You could continue to explore pitch with this Perfect pitch What’s Going On?, or explore the changing pitches of instruments in the string family with Playing high or low and String family.