This sound is /ks/, as in the word 'expect.' This is actually a combination of two sounds: the initial stop sound /k/ and then a continuous sound /sss/. Together that’s /ksss/. The International Phonetic Alphabet (IPA) represents these phonemes with the following symbols: ks. In the early stages of the curriculum, Once’s instructional content represents the sound with a symbol that is made by typing ‘x’ in a specialized font. This specialized orthography helps beginning readers (pre-kindergarten students through early elementary grades) learn letter-sound correspondence more quickly. By the middle stages of the curriculum, the specialized orthography is phased out and replaced by letters in a serif font.
