KTurtle (comes with most Linux distros). If your kids are not fluent in English, then KTurtle sports several languages through KDE's language packs. Both the co

KTurtle (comes with most Linux distros). If your kids are not fluent in English, then KTurtle sports several languages through KDE's language packs. Both the commands, docs and error messages are translated. It is a bit like LOGO, but with different syntax. If English is no barrier then https://code.world/ https://code.world/ is also pretty awesome, and in the browser. Disclaimer: I'm one of the devs of KTurtle.