We're about to embark on the Prepared Dictation voyage. Here's how it works....
at about age 9 or 10 you have your child do prepared dictation once a week. They will look at a passage, paying special attention to how words are spelled. After a bit they close their eyes to see if they can remember how the words look. If they can't, they look again at the passage and try to "take a picture" of the words. It might help to trace the word on the table with their finger or to spell it out loud. After they are sure they know how to spell the words, ask them to look at the punctuation and capitalization. When they've had enough time to do this, you will begin the dictation.
Read the passage slowly, stopping after a few words so that the child can write easily. As they get older you'll be able to read longer passages, but at first keep it shorter. If they make a mistake immediately cover it up (Post-its work well for that) and have them continue. When they have completed the passage have them correct the mistake either on top of the Post-it or YOU erase it and have them respell it. You don't want them to look at the misspelled word because then their brain takes a "picture" of it and they have a hard time remembering the correct way to spell it. If you do this casually and without criticism the child won't feel 'bad' about getting things wrong.
I have prepared a "book" to help me do this. At first the dictation passages are short and in large print so the boys will have an easier time studying them. As they move further along the path, the passages become longer and the font reduces to more normal sizes. I've chosen to include several passages per page merely for the purpose of saving ink and paper. I intend to cover up the passages they are not working on so they don't get confused. I have noticed that many dictation books have one passage per page, but I was trying to be frugal here. I have done my best to make sure paragraphs or quotes remain o n the same page. For example, the beginning of the Declaration of Independence is several paragraphs long. Two or three fit on a page, then I pushed the next paragraph to a new page so it would not be divided. You can choose to have your kids do one paragraph at a time, or learn the whole thing (for older kids).
You could also use these lists for copywork. I have! I print them up and cut them out and stick them in my Copywork Jars. Every day the boys take out one or two strips of paper and copy them into their books. I'll post the other pages I've made for the Jars soon.
These lists would also make a great memorization tool.
One thing I want to do with dictation is to create a meaningful book of scripture, advice and encouragement. I've tried to keep all the quotes uplifting and worthwhile so that (hopefully) they will look back over this in years to come and find peace and guidance in the words.
I have prepared one file for with verses from the King James version of the Bible, with other quotes, etc and one for those who are LDS (Mormon).