Student One replaces words with other familiar words. Although he can identify a word when it is on its own, he often confuses high frequency words when written in a sentence. This would go hand in hand with practicing high frequency words so that he is able to recognize them in texts. I would review high frequency words and then have the student write them in a sentence.. I would also have him re-read this book to see if he doesn't actually know the word can or is he was just distracted. I would also have him read to me and point to each word as he is reading it.