Aufgabe 7: Telegraph


The task sheet is an introduction to communication engineering: from a simple light signal through a number signal to the transmission of
a coded message. Sub-programs (“own blocks”) in Scratch are introduced for this. The task is particularly suitable for working in pairs with one transmitter and one receiver unit.


How can signals be transmitted? How are messages coded? What are sub-programs and how are they used in Scratch? How can time be measured in Scratch?

Learning objective

  • Principle of (asynchronous) signal transmission
  • Understanding how messages are coded
  • Transmission of a message as a sequence of characters
  • Use and programming of sub-programs in Scratch
  • Time measurement in Scratch

Time required

Set-up of transmitter and receiver only takes a few minutes. Tasks 1+2 can be solved during the rest of the lesson.
A further lesson should be planned for tasks 3+4.

The experimental task is simply the application of the programs from tasks 3+4, but manual coding of the message takes time. For this reason, a further lesson should be planned for processing this task.

Didactic material