This word work is good for all ages you just change the difficulty of the words. I use these (available on Amazon) but you can use any kind of letter tiles or print them on card stock.
Now for another secret...
I get my words from the Making Words books. You can get the word lists for free by googling Making Words table of contents and your grade. This website will come up and you can download the table of contents which lists what the mystery word is for each lesson. http://www.christianbook.com/