At some point during the early elementary school years, children begin to use more and, according to the fuzzy trace theory, this contributes to the improved memory and reasoning of older children.

The answer to this question is "Gist" which means essence or substance. As per the Fuzzy Trace Theory, at some point during the early elementary school years, it was observed that the children begin to use GIST more and this attributes to the improvement of memory and the reasoning skills of the children at this very early stage.