My personal experience with coding has been limited to using HTML and taking a course on a CD to learn Basic, which I never used afterwards. I used HTML to create Teach the Children Well as well as Cape Cod Photo Album and European Photo Album. I first learned HTML back in 1999 and other webpage editors didn't really make sense to me. Since then, I have learned to use Blogger (Thank You Teacher, Plymouth Kids, Teach the Children Well Blog, and Massachusetts Field Trip) Google sites (iPads for Elementary Classrooms , Tech Curriculum Map, and American Revolution People) and Apple's iWeb, with which I created Vacation Photo Albums. Even when I use editors, I sometimes am able to tweak the sites by using HTML, for example to add an email link to a Google site.
I used to teach fifth graders some basic HTML by copying a page that I created about the Original Colonies. I also gave them a sheet that explained the purpose of the various tags. The webpage included a graphic of a map of the Original Colonies, a few basic facts about one of the colonies, and links back to a source for the information. My purposes for this task included typing accurately and proofreading, basic research, citing sources, and of course, an introduction to coding.
Just as there are editors so that using HTML is not the only way to create websites, there are visual coding programs. I used MIT's Scratch with fourth and fifth graders. I introduced it to them by showing them a few very basic moves and how to put together the blocks and change backgrounds. I printed the Scratch Cards and encouraged, but did not require, them to use them to get started. One especially nice thing that happened was that a particularly shy boy had had some prior experience using Scratch at the Y and was able to take a leadership role helping others with it. The students were free to explore Scratch and create with it and really seemed to enjoy using it.
I also played around a bit with Alice, which was created by Carnegie Mellon. There are some nice tutorials built into Alice, but after I completed them and tried to use it on my own, I found it frustrating so I never used it with kids.
In a class I took, I learned about BeeBots programmable robots which can be used even in Kindergarten. There is a free Bee-Bots app for the iPad. They use Logo, a programming language that I'd pretty much forgotten about. Logo is also the basis for MicroWorlds. NetLogo and StarLogo also use this language.
Google has also created a coding site, Made with Code, particularly with girls in mind.
Hopscotch is a coding program for the iPad similar to Scratch. Kodable is another visual programming iPad app for children as young as five.