Build a micro:bit seismometer and record a classroom quake

The idea

A seismometer records ground shaking against time; a home-built one shows that the record's size falls with distance from the source, while locating a real earthquake needs arrival times at several stations.

What you need

• 1 BBC micro:bit with battery pack per group, a laptop with the MakeCode editor and the Geoscience Australia micro:bit seismometer teacher guide (catalogue record 149029)
• a long table or bench (2 m or more), with the micro:bit fixed flat at one end with adhesive putty; the Geoscience Australia guide finds the micro:bit good at sensing vibrations in tables and chairs but poor at sensing them through the ground
• a rubber mallet, or a small mass dropped from a fixed height, to make the 'earthquake' at marked distances (0.5 m, 1.0 m and 2.0 m from the sensor) along the table
• a tape measure

How to do it

1. Load a seismometer program onto the micro:bit (the Geoscience Australia activity, or a MakeCode program that logs the accelerometer strength against time) and fix it flat to one end of the table.
2. Tap the table, or drop the mass, with the same strength at 0.5 m from the sensor, five times; save each trace and read the peak.
3. Repeat at 1.0 m and 2.0 m.
4. Plot the peak against distance for the taps at each distance (mean and range), leaving out any tap that shows no spike and recording how many there were.
5. With two micro:bits at the two ends of the table, tap between them at an unmarked point and use the two peak readings to say which sensor is nearer; check with the tape. The two boards' clocks are not synchronised, so their arrival times cannot be compared.

What you should see

Taps near the sensor give a clear spike above the resting trace. The program reads the accelerometer at intervals in a loop, so a short tap can fall between readings and be under-read or missed, most often at the far mark; that is why each distance has five taps and misses are counted. The mean peak usually falls with distance along the table, the pattern the Geoscience Australia guide asks classes to look for, and the guide notes that the micro:bit senses vibrations in a table far better than in the ground. With two sensors the nearer one usually records the larger peak, so the tap point can be placed on the nearer side; locating a real earthquake uses arrival times at three or more stations instead, as in the S minus P practical. The learner knows it worked when the mean peak falls from the nearest to the farthest mark and the two-sensor test names the nearer sensor in most trials.

What changes

What you change

distance from the drop

What you measure

peak acceleration recorded

What you keep the same

• tap strength (the same mallet swing, or the same mass and drop height)
• table surface
• sensor mounting

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

• A seismometer measures how far away the earthquake was directly; it records shaking, and distance comes from timing.
• Small tremors are not real earthquakes; the same physics records both.

Safety card

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 7-10 Syllabus (2023), NSW Education Standards Authority (implemented from 2026; codes read at curriculum.nsw.edu.au on 22 and 23 September 2026)SC4-CHG-01SC4-DA1-01SC4-WS-01SC4-WS-05
• Australian Curriculum v9AC9S8U03AC9S8I03AC9S8I04

Sources

The pages the author read to write this activity.

1. curriculum.nsw.edu.au/learning-areas/science/science-7-10-2023/outcomes
2. vocabulary.curriculum.edu.au/MRAC/2024/04/LA/SCI/export/MRAC/2024/04/LA/SCI.jsonld
3. pid.geoscience.gov.au/dataset/ga/149029
4. d28rz98at9flks.cloudfront.net/149029/149029_00_1.PDF
5. www.ga.gov.au/education/classroom-resources/earthquakes-teacher-notes-and-student-activities
6. www.iris.edu/hq/inclass/fact-sheet/how_are_earthquakes_located