What is the optimal way to run the Piaget Conservation of Number Task? I am hoping to run a standard Piaget conservation task to test the conservation of number.  The task is as follows:


  Coins such as pennies are placed on a table. A certain number of
  coins are placed in a row, and a matching series of coins is placed
  directly below the first one. So there are two equal rows of coins on
  the table. Now the experimenter spreads out one of the rows so the
  coins are farther apart. The child is asked whether the two rows of
  coins still have the same number of coins in them. A small child who
  does not yet know how to count will typically claim that the
  spread-out row has more coins in it.


Previous studies are quite varied in several ways.  First, in the number of coins that are presented (typically it looks like it is 5-8). Second, how many trials are performed. Third, how many trials must a child pass/fail to conclude that he or she does or does not conserve number. 

Therefore, I am asking for advice on the ideal protocol for running this task (i.e. trial types, number of trials, pass/fail requirement).
Particular attention should be given to the theoretical framework (Piaget's Theory and constructivist perspective), hypotheses to contrast (levels), information gathering and common difficulties.

"Levels" in quantity conservation test:

Level of absence of term-to-term correspondence:
4-5 years.
Simple intuition.
Consider the global and static configuration of the rows (not quantity of chips or accounts).
They are limited by the configurations of the tabs.

Level of correspondence term to term without conservation:
5-6 years
They establish correspondence 1 to 1 in both rows, before the transformation of them, they break the equivalence.
They focus on aspects such as density or length.

Level of non-durable conservation:
Around 7 years.
They are conservative in some situations, depending on the context.

Level of conservation required:
7 years.
They are persevering and gives evidence of compensatory behaviors (length / density) or reversibility (join / separate).

The count for Piaget is a social skill with no logical mathematical content (concept of number). It would be necessary to differentiate between logical structures or schemas (classification, seriation and number) and infralogic structures (substance, weight, volume, space). Often smaller children count simply by saying the words: One, two, three, etc. as if it were a song but they do not follow any order or logic. Other times, although the child already has numerical structures developed, errors occur. The final step is when the reversibility of the transformations (deformations, displacements or fractions) is established. THEORETICAL FRAMEWORK SHOULD BE VERY WELL ESTABLISHED.

ALWAYS MUST ASK FOR REAFFIRMATION AND ASK WHY THE ANSWER HAS BEEN GIVEN (but not so that the child thinks that perhaps he is giving an erroneous answer). YOU MUST PRACTICE SERIOUSLY BEFORE THE TEST.

Leaving aside the presentation of the test that you could present as a game (and try to make it really fun) try to follow the words or terms that the child expresses, once the child responds do not add other terms, sometimes there is distraction for some concepts said by the experimenter.

Keep in mind common difficulties in test with children: Lack of attention or motivation and distractions (many children can pay close attention to their mom or dad or they can go to the test with their favorite toy).