Extendable Bonko

Educational objective

To see how the length of a tube affects its pitch, and the amount of force you hit it with affects its loudness.

Extendable Bonko activity sheet

Download student activity sheet [pdf]

Key student learning

• When you hit a tube, the column of air inside vibrates. This vibration travels to your ears and you hear it as sound.
• The shorter the tube, the higher the pitch of the sound, and vice versa.
• The harder you hit the tube the louder the sound, and vice versa.

Materials needed

• 1 empty crisp tube
• 2 A4 sheets of thick paper or thin card
• Tape

Practicalities

• A crisp tube is ideal for this activity as it has a strong metal base that gives a good ring when it is hit. A hard-wearing alternative would be to collect and wash empty tins and join these together into a long tube. This will require removing the bases on all but the bottom tin and taping them together. Care is needed to make sure that the cut ends are taped so that they are not sharp.

Open-ended investigation

For a more inquiry-based activity, challenge the children to make a musical instrument that can play a range of notes using only the crisp tube, card and tape supplied. Click here for a guide to planning open-ended investigations in your classroom.

Discussion

• When you slide the card tubes up and down the crisp tube, how does that affect the sound?
• How can you make the sound louder or quieter?

Extensions

• What are the highest, lowest, loudest and quietest sounds you can make with the materials you have? What do you need to do to the tube to achieve these?
• If you wanted to make the pitch higher, what could you do? What is the highest note you can play with these tubes given enough A4 paper?
• What do you need to do to make the sound even lower? What is the lowest sound you can produce?
• Can you mark the tubes at different pitches and use this to play a recognisable tune?

Click here to download an inquiry-based learning version of this activity.

Links to everyday life

Trombones and other wind instruments, such as swanee whistles, produce sound by vibrating a column of air which can be lengthened or shortened. The longer the column, the lower the pitch.

Trombones and other wind instruments, such as swanee whistles

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