If you write a blog post in Word or Pages, when you go to copy it into Blogger or WordPress (including Edublogs and Kid Blog) don't copy it into the "Compose" editor (Blogger) or "Visual" editor (WordPress). If you copy it from Word or Pages and paste it into "Compose" or "Visual" you could be bringing along some background code that will alter the way that your post's text and other visual elements appear on the blog. What you should do instead is paste the content into the "HTML" editor (Blogger and WordPress use the same terminology here) which will reveal any strange code that shouldn't be in the post. What you should see is just the text of your post and possibly any embed code for a video or HTML for an image. If you see anything else around your text and especially between pieces of text, delete it. To preserve paragraph spacing simply insert <br /> between paragraphs while you're in the HTML editor. Before you hit "publish" on the post you can switch back to "Compose" or "Visual" to make sure your spacing is correct and or to style your font. This might sound like a lot of extra work, but it really isn't and in the long run it will save you the frustration of trying to sort out formatting issues with your blog posts.
If you have Google Drive enabled for offline composition of documents, write your blog posts in it when you're offline. I've always been successful in simply copying and pasting text from Google Documents into the Compose editor on Blogger and Visual editor on WordPress without any formatting issues.