This concept explicitly teaches us about the ‘ai/ay’ spelling rule. As a general rule, when isolating the sounds of a word that contains the long /ā/ sound, the written letters we choose will depend on where we hear this sound in the word. If the sound is at the beginning or in the middle of the word, the written letters will be ‘ai’ such as t-r-ai-n. However, if we hear the long a sound at the end of a word, the written letters will be ‘ay’ as in ‘play’. Most of the time, if we hear /ā/ at the end of a syllable, the written letters also need to be ‘ay’ such as cray/on.