Science and Technology K–6 · Years 1–2
Muffling sound: which material blocks it best
Physical World, energy comes in different forms that can be detected (NSW 2017); Science understanding, Physical sciences (ACARA v9)
The idea
Sound passes through some materials more easily than others, and a fair test with a meter ranks them.
What you need
- A kitchen timer that rings, or a phone playing the same 10 second tone at a fixed volume
- A shoebox to hold it; wrapping materials: a folded towel, bubble wrap, a sheet of cardboard, aluminium foil, a woollen jumper
- A sound-level meter app on a tablet 50 cm from the box on a stand. A free app on a tablet is not a calibrated meter, so its readings are used to compare one wrapping with the next and never read as a decibel figure for the material
- Recording table: material, reading (dB), three trials
How to do it
- Play the tone in the open box with no wrapping. Read the meter. Three trials.
- Wrap the box completely in one material and play again. Three trials. Repeat for each material.
- Circle the middle reading for each and order the materials from most muffling to least.
- Predict which would make the best ear muff and test by wrapping the box in two layers of the winner.
What you should see
Wrapped readings are lower than the open-box reading, and two layers lower it further than one. Which material muffles most is the class's measurement; soft, thick materials such as the towel and the jumper are expected to muffle more than thin foil. The order of the materials and the direction of each change are the result; the size of the drop in decibels belongs to the room and to an app that is not calibrated, so it is not reported as a figure for the material. The learner knows it worked when the open box gives the highest reading in every trial and two layers beat one.
What changes
- What you change
- wrapping material (none, towel, bubble wrap, cardboard, foil, wool)
- What you measure
- meter reading (dB)
- What you keep the same
- same tone and volume
- meter at 50 cm
- box fully wrapped each time
- three trials
Common misconceptions
Each of these ideas is wrong, and the activity is a chance to test it.
- Sound cannot pass through solid things at all.
- Foil blocks sound because it blocks light.
Safety card
Hazards
- None beyond a ringing timer
Controls
- Volume kept moderate
Note
No chemicals or heat. Record the activity on the school's risk assessment (Primary School RiskAssess, Ecosolve Australia, riskassess.com.au).
Curriculum references
The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.
- Science and Technology K-6 Syllabus (2017), NESA. Current syllabus; NESA's timeline is 2026 plan and prepare, 2027 start teaching the 2024 syllabus. Code read from the official syllabus document on 2026-09-22.ST1-8PW-SST1-1WS-S
- Science and Technology K-6 Syllabus (2024), NESA. Implementation from 2027, so this code describes the future syllabus. Code read from the outcomes page on 2026-09-22.ST1-SCI-01ST1-PQU-01ST1-DAT-01
- Australian Curriculum v9AC9S2U02AC9S2I01AC9S2I02AC9S2I03AC9S2I04AC9S2I05AC9S2I06
Sources
The pages the author read to write this activity.