Design an alarm for your schoolbag

Use the BBC micro:bit programmable system to create a working prototype

This is one of a series of resources to support the use of the BBC micro:bit in Design and Technology lessons.

Schools are busy environments and it is easy for learner’s bags to be left unattended, taken by mistake or even stolen. Alarm systems using embedded electronics and programmable components can be developed to protect the property of learners during the school day.

In this unit of learning, learners will research, program and develop a working school bag alarm system using the BBC micro:bit.


In this activity, learners will develop their programmable system using the BBC micro:bit and the device’s inbuilt accelerometer to detect movement.

The activity sheet includes teachers' notes, useful web links, and links (where appropriate) to the national curriculum in each of the four devolved nations; England, Northern Ireland, Scotland and Wales.


Keep off that bag - Exploring how accelerometers within small devices such as the BBC micro:bit can be used to detect rapid changes in movement and set off the alarm if the bag is moved.

Watch at


  • Activity overview - Design an alarm for your schoolbag activity description, teachers' notes and curriculum links
  • Presentation - Developing the system using the BBC micro:bit accelerometer
  • Handout - Developing the system - student handout with example programs from the various editors available
  • Hex programming file - Example programming file using the MakeCode editor
  • Py programming file - Example programming file using the Python editor
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