Motivation is based on respect.

Why are your pupils coming to school? What is their motivation?
Some love to go to school, because you as a teacher are able to
create a good atmosphere in your group.
You challenge your children to do the things they are able to.
Of course you don’t ask them to do what they can’t .
There is no child that wants to demonstrate the things they can’t do.
Every child knows that it is unwise to enter into this risk.
Children don’t go to school to score.
You want them to score, but they don’t.
Children go to school to go through a deal.
Is something special happening ?
They don’t remember you later as the teacher who made excellent
assignments or tests, but as the teacher who played the piano
so beautiful , played football during the school camp, or you
were the teacher who did the things that were important for
them personally.
Teachers and pupils meet each other in the first place as persons,
they judge each other on basis of personal values.
So education in the first place has inter-human importance and
at a second place an educational.
Helen Parkhurst simply said at this point : respect the child.
Only in a good relation children are able to show what they can.