Archive.png This article or section documents something not included in the current version of Scratch (3.0). It is only useful from a historical perspective.

Single Stepping was a tool in Scratch that ran scripts slower or faster, and performed each block individually. Single Stepping could be accessed through the "Edit" option in the toolbar.

What it Does

By clicking on "Start Single Stepping" it starts the process with the current option. By default it was "Flash Blocks (Slow)". These are all the possible options in could be set it to:

Turbo Speed

Main article: Turbo Mode (3.0)

In turbo speed, all scripts ran as fast as possible. This was very useful for speeding up mathematical projects, however makes features such as graphic effects and clicking on sprites lag quite a bit.

In the Flash Player, turbo speed was instead named "Turbo Mode", which was accessed by shift-clicking the Green Flag. Turbo Mode could also be accessed by clicking the Edit drop down list and clicking "Turbo Mode". This was much faster than the Squeak (offline) turbo speed, making projects up to 50 times faster. Turbo speed between the online and offline editors differs greatly.[citation needed]


Ran all the scripts as they would normally be; it's just like having Single Stepping turned off.

Flash Blocks (fast)

Ran a project at normal speed, however, when a block is active, it turned yellow. This was useful for debugging.

Flash Blocks (slow)

Ran a project extremely slowly, and turns blocks yellow when they are active.

How to Turn On

Before you zoomed in, you held ⇧ Shift and pressed the green flag.


This could be useful for:

  • Speeding up mathematical projects
  • Finding the source of a glitch
  • Finding out exactly how a project works
  • Humor and amusement


Main article: Detecting Turbo Mode

There are simple scripts that could be made that detect if Turbo Speed or Single Stepping is on.

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