This sound is /th/, as in the word 'that.' Make this a voiced sound. The unvoiced version of this digraph is /th/ as in ‘think,’ but it’s introduced later in the curriculum. The International Phonetic Alphabet (IPA) represents this phoneme with the following symbol: ð. In the early stages of the curriculum, Once’s instructional content represents the sound with a symbol that is made by typing ‘shift + t’ 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.