While you can use any version of Scratch, if you have a Raspberry Pi 4, we recommend using Scratch 3. Follow the instructions on the next page to get Scratch 3 on your Pi 4.
If you have an older Pi however such as a Pi 3 or older, you may not be able to run Scratch 3 because of the memory requirements of the program.
You can however run Scratch 2 which still has Raspberry Pi GPIO functionality, so skip to the section "Scratch 2" to find out how.
Once you are in the Raspbian desktop, you will open up Scratch 2 which comes preinstalled on the Pi.
To Open Scratch 2:
Click the Raspberry Pi icon on the top left of the desktop, then Programming>Scratch2
And that's it! Scratch is ready to go!
Open the More Blocks panel, click Add an Extension, and select Pi GPIO. You should then see two new blocks appear:
You can use these two purple blocks to control output pins or read input pins by entering the pin number into the field, or using a variable containing the pin number.
Next up, putting the spiffy new blocks to work.