Spelling Dictation

Taking sentence structures that we have done in class I dictate them 3 letters at a time. So for the sentence (I have to go to school) I would dictate it in the following manner, pausing briefly for a slash:

I H A / V E T / O G O / T O S / C H O / OL

They write down the letters - some will get in a muddle, some may hold their head in despair - but others will begin to see the sentence and start guessing what the completed sentence will be.