So, I am a little late on this post, but before Christmas my fifth graders participated in the Hour of Code, and they LOVED it! the Code.org website uses Blockly to introduce students to coding and how to tell the computer what to do using popular characters such as Minecraft, Star Wars, and Frozen. I had planned to do with each grade, but my technology teacher had the same plans. Great minds think alike! So, she is doing it now with 4th and then 3rd grades.
Some other resources that my son has used at home are the board game Robot Turtles, which requires zero technology and not even any batteries! Also, for Christmas, he got a Code and Go set from Learning Resources with a robot mouse that you code to go through maze challenges. Either of these could be great for a center or intro to coding for younger kids.
Here are some shots of my 5th graders coding away!