I remembered that this pasuk has hard words, so I pulled out a Chumash with English translation. Rashi explains it as being agitated, and I stuck with that explanation. 9 yo chimed in: "This word was used in Yehoshua".
"At Ai, when Achan took spoils. Hey, they took spoils here, and he took wrong spoils there. Maybe that's the connection."
He remembered learning about it in Sanhedrin, where it is talking about vidui.
Here is the pasuk that he was talking about: וַיֹּאמֶר יְהוֹשֻׁעַ מֶה עֲכַרְתָּנוּ יַעְכֳּרְךָ יְהֹוָה בַּיּוֹם הַזֶּה ( Yehoshua 7:25)
I wish I had memory like that. I wish 9 yo would apply his amazing memory to something other than Pokemon statistics. I wish I knew how to challenge him appropriately in his learning.