Find a list of words that your students are expected to know, based on their grade level. Choose 50 or more words that you are interested in exposing to your class. Feel free to mix in words from books you have assigned, words from a higher grade level list or words that will appear in a future curriculum. Arrange them alphabetically on a sheet of paper to form your master list.
Ask your students to take out a piece of paper for a nongraded spelling quiz. Read at least 20 words from the master list. Ask your students to spell the words, to the best of their ability, in a numbered sequence down the side of the page. Collect the quizzes and score them; do not enter the score in your grade book. Identify which words were misspelled most frequently and circle those words on the master list. Choose 10 to 15 of the words with the highest incidence of error; these words will be used to make your own spelling worksheet.
Open a word processor, worksheet generator, or other program that you will use to make your worksheet. Title the worksheet appropriately. Number the worksheet down the left margin to accommodate all the circled words on your master list. Divide the document into four columns. In each of the four columns, spanning each row in the numbered document, write four different versions of the word; three of the versions should be subtle misspellings, while one version should be spelled accurately. Mix up the order of the spelling variations, so that the correct word may be first, last, or somewhere in the middle of each row. Resize the font until the entire worksheet fits on a single page. Add margins to the column boundaries to give the document visual clarity, if desired.
Make copies of the worksheet, using a copy machine, and distribute the worksheet to your class, either as an in-class assignment or as homework. Ask the students to circle, underscore or check which of the four versions of the word they think is spelled correctly. Collect and score the worksheet; issue a quiz on the words, if desired, or expand on the worksheet by writing the words on the board and spelling them out loud with the class. Choose some of the unused words on the list you first developed and repeat the process until your class improves enough to satisfy your vision of adequate progress.