Blogs
Blogging is a quick and easy way to add your content to the web. There are quite a few free blogging sites that are easy to use.
I would advise signing up with an adult's e-mail address and turning off the ability for users to comment. It is great to let your kids set up the layout, templates, and colors once you have created the account.
WordPress - Free blogging site that has lots of features. I advise you not to let younger students on to the home page of Word Press since you never can tell what the featured blog of the moment is. A good feature of WordPress is that you can set your blog to be private and only give the password to those you want to see the blog. So if you aren't wanting your child's work to be viewed by the world, set the blog to private and only give the password to friends and family.
Blogger - Blogger / Blogspot is another very popular blogging site similar to WordPress. You can also turn off comments and set your blog to be viewable only by those you invite to see it.
Tumblr - This is a very simple blogging tool. It doesn't have as many features as other blogging sites, but it would be a good place to get your feet wet in the blogging world!
