These days I'm reading the novel THE LION, THE WITCH AND THE WARDROBE (纳尼亚传奇). In the chapter 5, the writer tell us how to cope with a child lie.
In the novel the youngest honest girl Lucy went to the Narnia World through the wardrobe. When she told the things she saw to his older brothers and sisters, they didn't believe her and thought she was telling a lie. What was worse, several days later Lucy's brother Edmund went there and met Lucy, but when he came back he wanted to let Lucy down and told his brother Peter and sister Susan that he never went there. There is no doubt that Lucy felt very sad. Peter and Susan also thought Lucy either told a tie or went mad. They didn't know what to do and told the whole thing to A Professor.
The professor said that a child who was honest and obvious not mad couldn't be assumed to tell a lie until any further evidence turned up. And he told the children to mind their own business.
I think it offers us a very suggestion to cope with a child lie.
First, it is better to assume a child not to tell a lie until some certain evidence to confirm it.
Second, for the action to tell a lie it is better to let it go on its way.