Choose a few sentences that contain the target language (vocabulary or grammar) you are working on in class. Tell the student to put a piece of paper over the sentences, then have the student look at one sentence for 5-10 seconds.
Cover up the sentences again and have the student write down what she/he can remember.
This exercise is helpful because the student must read it themselves, which helps to retain the word. If necessary, the student may look again at the sentence to be dictated.