Scratch is a programming environment from MIT designed as a way to introduce kids to coding. It takes care of the GUI side of things and lets kids focus on program logic, variables, control statements and functions. The newest version of Scratch is browser-based, but MIT still maintains the download page for version 1.4, the last downloadable version you can run on your desktop without an internet connection.
On the other side of the pond, in the UK, is Code Club, a volunteer-led network that runs free after-school programming clubs for kids age 9-11. Code club has built a solid curriculum that is available online at their GitHub page, enabling volunteers to focus on teaching rather than spending copious amounts of time preparing lessons. The GitHub curriculum has been field-tested and is based on the feedback of volunteer teachers. It attempts to deliver just the right amounts of fun and learning. Each lesson is designed to be 1 hour long.
Code Club’s 1st and 2nd term lessons are based on MIT’s Scratch. I spent a little bit of time playing with the first lesson on Scratch 1.4 (the written instructions for the lessons seem to not have been updated yet for 2.0, though they could be easily adapted by a teacher for use with the browser version). On 1.4, following the written lesson instructions was a cinch, and sharing my work on the Scratch website was arguably the funnest part (I had forgotten you could do that). Check it out!
[Edit] Check out Wasdkeys123′s remix of Felix & Herbert.