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Technologies K–10 · Years 5–6

Sending a message in packets across the classroom

Digital Technologies (NSW Science and Technology K–6, 2017); Digital Technologies: Knowledge and understanding, Digital systems (ACARA v9)

Practical, model not builtLow risk

This site has no interactive model of its own. Where a step or a material names a Concept Studio model, simulation or tool, it has not been built; an external simulation a step names (for example PhET) is not part of this site.

The idea

Networks send data in small numbered packets that may travel by different paths and arrive out of order, and the numbers let the receiver rebuild the message and spot a lost packet.

What you need

  • Message strip: 'MEET AT THE LIBRARY AT LUNCH AND BRING A PENCIL.' (48 characters including spaces and the full stop)
  • Packet cards with header boxes: to, from, packet number, total packets, and 8 boxes for characters
  • 3 desks labelled as routers between the sender and the receiver
  • Envelopes

How to do it

  1. The sender splits the message into packets of 8 characters and fills in the header on each card.
  2. Packets go to the routers in any order; each router passes packets on by any free path towards the receiver.
  3. The teacher quietly removes one packet on the way.
  4. The receiver sorts the packets by number and writes out the message.
  5. The receiver works out which packet is missing and sends a 'resend packet N' card back.
  6. Repeat, sending the whole message on one card that the teacher removes, and compare.

What you should see

The 48-character message becomes 6 packets of 8 characters. Packets arrive out of order and the receiver rebuilds the message by packet number. The missing packet is found because one number from 1 to 6 is absent; only that packet is resent. When the whole message travels on one card and it is lost, nothing arrives and everything must be resent. The learner knows it worked when the rebuilt message matches the original exactly.

What changes

This activity lists no variables to change, measure and keep the same.

Common misconceptions

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

  • A message travels along one wire from start to end (packets can take different paths).
  • Packets always arrive in order (the numbers are needed because they often do not).
  • If part of a message is lost the whole message must be sent again (only the missing packet is resent).

Safety card

Low riskLearners carry it out

Hazards

  • Moving around the room

Controls

  • Walk between desks; bags off the floor

Note

No chemicals or heat.

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. The syllabus taught in 2026; the 2024 syllabus replaces it from 2027. Code read from the official syllabus document (DOCX) on 2026-09-22.ST3-11DI-T
  • 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.ST3-DDT-02
  • Australian Curriculum v9AC9TDI6K02

Sources

The pages the author read to write this activity.

  1. www.nsw.gov.au/education-and-training/nesa/curriculum/science/science-and-technology-k-6-2017
  2. curriculum.nsw.edu.au/learning-areas/science/science-and-technology-k-6-2024/outcomes
  3. www.digitaltechnologieshub.edu.au/search/there-and-back-again-a-packet-s-tale-how-does-the-internet-work
  4. classic.csunplugged.org/activities/network-protocols

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