Sounds like you're looking for the Gemara on Shabbos 104a.
The Rabbis told R. Joshua b. Levi: Children have come to the Beth
Hamidrash and said things the like of which was not said even in the
days of Joshua the son of Nun. [Thus:] alef Beth [means] ‘learn wisdom
[alef Binah];Gimmel Daleth, show kindness to the Poor [Gemol Dallim].
Why is the foot of the Gimmel stretched toward the Daleth? Because it
is fitting for the benevolent to run after [seek out] the poor. And
why is the roof of the Daleth stretched out toward the Gimmel?
Because he [the poor] must make himself available to him...
iTalmud app translation
Also, I don't think they're talking about real children, but rather, younger generations that discover new hidden meanings in the Torah, which weren't taught in the traditional oral-torah of previous generations.