I assigned each page a letter of the alphabet. Be sure to teach them to pronounce any words that they can't say. Also if you have an excellent dictionary, the history of the word can be explored a bit. If you deem it necessary, you can also have the children tell which part of speech the word is as it is used in their sentence. Some of the thesauruses tell the part of speech while others do not.
Many words have more than one part of speech.
Sometimes the part of speech can be changed by adding a suffix. We usually do two words a day. On Fridays, I let them choose the words. Also, on Friday, you can have the children put their new words in alphabetical order if they need practice in that area. To prepare for this, all you need to do is thumb through the thesaurus and find a couple of words for each day.