There are different points of viewregarding thisquestion. Somebody say that we need to tell all the truth for children, somebody doesn't  agree with it.

We teach our children to be honest, and when we lie, they will take an example from us. They will think to lie it is a norm, and they will think that everything will be ok, if they lie.  There are a lot of films which teach us to tell the truth,  and any stories end with that everyone will know the truth. 

From my point of view we need to tell the truth but sometimes not all the truth. Also we should  take into consideration the age of the children. Because the truth cannot be the best solution in certain situations.  I will tell the truth for children, I will try not to lie them, because sooner or later the secret is revealed! We must remember about it. And if I tell them the truth we will have a trust relationship!