start a different topic in the course of a conversation or discussion

I tried to change the subject by commenting on the lack of activity in front of our position.  BNCI

At the stage of our acquaintance I was unaware of when to change the subject.  BNCI

Every time I tried to change the subject, she'd close her eyes, hold up her hand and say, `;I haven't finished yet.';  BNCI

talk rapidly about nothing very important

Dani can help me with the actualpreperation and I will chatter like a magpie so you know why somethingis being done. WebC

I used to chatter like a magpie about emancipation, and wasted half my wealth on tender feelings, but now--you must excuse me!  WebC

When we take care of him, he will chatter like a magpie; he will jump likea kid, and he will eat everything. WebC

(sth is) extremely easy

It was a child's
play, chosen to conceal a deeper game on Frank Churchill's part. google

 For us it was a child's play. Google

It was a child's play to find the classroom.  google

children should be quiet and respectful in the presence of their elders

Sure, while I was growing up my parents believed that "children should be seen but not heard."   WebC

He said the old adage that children should be seen but not heard does not hold anymore. WebC

An even older, lingering, idea is that children should be seen but not heard." WebC