Key behavioral indicators are looked for in the research.
Dr. Cavalletti comments (From Way of Holy Joy):
In all of these diverse environments the child’s response has always been the same and refers us back to what was said above: it is a response composed of complete satisfaction, meditative silence, and deep joy. 37
With the passage of time we came to realize that some themes were perceived with particular intensity and joy by children in the three to six age group, others in the six to eight age group, and still others in the nine to 12 age group. These themes were ones for which the children had an insatiable hunger. They returned constantly to the materials for these and responded to them with such seriousness and depth, as we tried to describe above. This was how a list of themes began to take shape, the themes that seemed to respond most fully to the vital needs of children at the various levels. 46
We recognized, with wonder, that the themes which the children receive with such naturalness, depth, and joy are the greatest ones. 47
Therefore, in forming a list of the themes, nothing was preprogrammed, nothing in the nature of devising a list (according to our way of thinking) and then passing it on to the children. 46
Thus our work consisted in stripping away many secondary elements we were giving to the children (to which the children remained indifferent and the materials languished on the shelves), to concentrate on the essential, … 47
This search for the essential led us to change paths more than once and to eliminate superfluous materials. 47