Depending on their age, for young kids best results I've had are Pi's (or old/cheap pc's) that boot straight into scratch. Far better results than an intimidating command prompt.
I second this. My kids love scratch. It shows them event driven programming with quick returns. The can also share their apps and download others so they can download and modify.
How old are the kids? Mine is just turning 5, and I've been looking at this as an option, but as many have said, I don't want to feel like I'm 'forcing' the tech learning on him.
Scratch is good from around age 8 to 14 or so, depending on their ability. Most kids don't even know they're learning, scratch is really fun. Coder Dojo has some great lessons, eg this one to make your own version of plants v zombies:
https://scratch.mit.edu/
Alternatively Pi's (or old/cheap pc's) that boot straight into Minecraft Eduction Edition:
https://education.minecraft.net
This has paths for the very young in minecraft itself to older kids using ide's.