Teaching this skill
Make the blank a listening prompt, not a guess.
A consonant–vowel–consonant word gives early readers a compact place to blend three phonemes and connect each sound to a grapheme. Say the whole word naturally, ask the learner to stretch it without adding an extra sound, and isolate the middle phoneme before choosing the vowel. After filling the blank, blend the completed word again.
Have the learner stretch the word, identify the middle phoneme and select the vowel before writing. The blank is a prompt to listen, not a guessing slot.
Watch for this pattern
A wrong answer is evidence, not a label.
A learner may know the letter name yet confuse the short vowel sound. Contrast two words with the same consonant frame, such as cat and cot, and listen for the changed middle sound.
Check a small sample before assigning another full page. Group similar errors, model the missing idea with one example, and then use a fresh short version to see whether the learner can transfer the correction.