I decided to integrate my "Word of the Day" program with their daily writing journal. As soon as the students arrive, I announce the "Word of the Day" and we discuss the meaning of the word and create synonyms for better understanding. At that time the students are to write anything they'd like; but integrate the "Word of the Day" into their writing at least twice by thinking about how the word pertains to them. For each day I created a journal template in which they write the date, "Word of the Day" and their entry.
By the end of the year, we will have a journal with over 160 entries and an expanded vocabulary. I use higher-level words to enhance their writing vocabulary; but you could also use this strategy with their science, math and reading vocabulary words.
Here are some photos of our "Word of the Day" journals: