I’m so glad to read that you’ve taken the time to determine the nature of the reading problem this student is having. It’s powerful information to know that he knows his letter sounds and is able to blend sounds together. His behavior of reading by filling in words that start with the same initial sound as the one in the text suggests that while he might be applying some of his letter sound knowledge, he’s not applying it to the entire word.
This student would benefit from two types of instruction: metacognition training and some type of word study. Ideally, as students read, they’re monitoring their understanding of what they’re reading. When something doesn’t make sense, they stop, go back, reread and correct, and keep going. The ongoing awareness of their understanding refers to metacognition, or thinking about thinking.
Several of the strategies we outline in our Classroom Strategies section help develop students’ metacognitive skills.
Strategies such as Listen-Read-Discuss, Possible Sentences, Structured Notetaking, and Question-Answer Relationship (QAR) all involve the student in thinking about the text as they’re reading. Perhaps if your student begins to do this, he’ll understand that the words he’s filling in do not make sense.
Instruction in word study will help draw your student’s attention to word parts and can be expanded to include word origins. This type of word study will help him break apart words more meaningfully, and perhaps be less likely to fill in words that don’t make sense.
Teaching Exceptional Children published a case study of word study instruction with older students: Adolescent Literacy: Wordy Study With Middle and High School Students . Word Study and Reading Comprehension: Implications for Instruction is another piece that might provide you with good information on this topic. There is a helpful, brief section on word study in Effective Instruction for Adolescent Struggling Readers (see pages 5-7).