CHILD LEARNING--"It is interesting to study how children spontaneously learn to measure. One of my collaborators, Dr. B¿rbel Inhelder, and I have made the following experiment: we show the child a tower of blocks on a table and ask him to build a second tower of the same height on another table (lower or higher than the first) with blocks of a different size. He begins to look around for a measuring standard. Interestingly enough, the first measuring tool that comes to his mind is his own body. He puts one hand on top of this tower and the other at its base, and then, trying to keep his hands the same distance apart, he moves over to the other tower to compare it. Children of about the age of six often carry out this work in a most assured manner, as if their hand could not change position on the way! --Jean Piaget"