"why are so many more Palestinian kids dying?"
Don't know for sure, although I suspect that if the IDF made a habit of surrounding their troops and armored vehicles with unarmed Israelis as shielding, like the Palestinian militants do, the toll would be a lot more even.
It is significant that other terror groups also rely on Western armed forces being reluctant to fire indiscriminately into a crowd of civilians, and use them for shielding in attacks. A common technique in Iraq, until we started using sharpshooters. Hello, Israel? The secret word is "sniper" not "helicopter missile."
That the terrorists would not hesitate to mow down a hundred civilians to get at a target goes without saying.