Using "read more" feature
From Georgetown University Commons Knowledge Base
The "read more" feature allows you to shorten the length of your blog posts by including a divider that hides (and upon click expands) the rest of your text. You can use this feature when you'd like to make it easier for readers to browse through your posts.
Adding a "read more" divider to a blog post
If your blog posts run long and you'd like to truncate them with a "read more" option, select the place in your post that you'd like the link to appear. Above the editing box, find the icon of two pages being divided by a dashed line. Click that, and you'll find that a dashed line is inserted into your post, dividing the visible content at the top (the "preview") with the content at the bottom. Readers of your blog post will need to click on a "read more" button to read the rest of the post.