I taught my 9yo sister to SSH from my Arch Linux system to an Ubuntu system, she was amazed to see terminal and Firefox launching remotely. Next I taught her to murder and eat all the memory (I love Linux, as Batman, one should also know the weaknesses). Now she can rm rf / --no-preserve-root and the forkbomb. She's amazed at the power of one liners. Will be teaching her python as she grew fond of my Raspberry Pi zero w with blinkt and phat DAC, making rainbows and playing songs via mpg123.
I made her use play with Makey Makey when it first came out but it isn't as interesting. Drop your suggestions which could be good for her learning phase?

Never erase a f*c%ing python installation on you Linux distro, its not funny.

After some time, planning to install Linux again for personal use and some dev work at home. My current pc is getting too slow sometimes and it irritates me a lot.

My current pc 2gb RAM, Dual core Intel, 32 bit.

Main criteria, os should be fast, I can compromise on GUI, should be stable, should support my old configuration. I like to work on Java/Scala, python, js and sql. Eclipse will be there since I use it at work.

Short listed Ubuntu 16.04.2 LTS,
mint (huge confusion on gui),
Opensuse, elementary OS and arch. I had Ubuntu, mint for some time as secondary OS. Arch will be totally new world for me. I have tried few OS in USB boot but couldn't fix one.

Right now I am confused about which one to choose, since everything looks fine but I want the best choice based on my criteria.