Erhua
From Wikicliki
儿化
"Several years ago (around 1995), I had a primary school Chinese textbook published by the Singaporean Ministry of Education (it was a prescribed text at my Saturday Chinese school in Melbourne, Australia). It was a grade 3 textbook and consisted of short stories (the grade 1 and 2 textbooks were focused on words/sentences). It had 儿化, but it was marked in smaller font eg 小孩儿 would have appeared as 小孩儿."