If you cease
For example, to nod food, to wind the head no.
Do not stop the trying, even if progress very slow; note any signs of improvement.
If you cease to teach it it will have no other opportunity to learn.
If you decide that the child is incapable of something he never and will not be able to do it.
Remember how you learned to swim?
Many months you considered that to you beyond its powers, and were surprised: how others can swim?
And suddenly at you it turned out and you cannot understand any more that here the difficult.
.