What is good system for teaching kids code?

I would like to teach my granddaughter, who is 10, how to code software.

What are the good systems available, that would be enjoyable for kids her age?  I started with Fortran 4, and have since gone on to dBase/FoxPro, php/mysql   -  so I've learned it the old-school way.  

I know that there are all sorts of initiatives and methods today - I would appreciate knowing the best.

Thanks.