The pinyin initials z, c and s form a pronunciation group distinct from zh, ch and sh.
A contrast to listen for#
The tongue is farther forward for z, c and s than for the retroflex group. The i in zi, ci and si is not the same vowel sound as the i in ji.
Suggested practice#
Compare zǎo with cǎo, and then compare sì with shì. Use a speaker recording to hear the contrast rather than treating the letters as English sounds.
Reference#
Pronunciation reference. The practice instructions here are newly written. Recordings, charts and illustrations from the reference are not reproduced.