The Essential 55 includes basics rules pertaining to respect, manners, and an appreciation of others. The lessons can be used with anyone, not just children, to increase productivity and positive human interaction.
The rules are not sequential so they can be worked on simultaneously. As with any new skill they must be explained, practiced, and enforced daily.
Mr. Clark makes reference to and takes examples from the classroom throughout the pages of his book; however, life can be viewed as a "classroom" in the larger sense of the word, thus the rules can work outside the traditional classroom.
The ideas presented here truly follow the golden rule. "Do unto others as you'd have them do unto you." Each of the rules would make communication so much more pleasant.
For example Rule #8, "Do not smack your lips, roll your eyes, or show disrespect with gestures." I'd love to imagine a world without teenagers doing any of these disrespectful behaviors but it must start with our having high expectations.
One way homeschoolers could utilize this rule list is by having children use them in their copy-work. I can imagine some very interesting conversations started by parents requiring compliance. Kids like to know what's expected of them (actually adults like that too), so these rules can remind us to tell children specifically what we will require of them and noting what we will require of ourselves.