While the child
Previously such pronunciation can be trained with from the covered mouth in front of the mirror.
While the child says syllables, you big and average fingers of a hand press on his cheeks, pressing them to the radical to teeth, and this movement push his lips a little forward.
In this situation instead of ti ti ti it will be heard chi chi chi.
Warn the child that sounding of a sound t' will change, and before lay down together to look, what sound as a result will leave.
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