There are a few salient differences between Israel and US that may confuse students initially:
1) The American system is highly stable. Elections at predictable times; no sudden changed in national election laws. Israel has tinkered with the system repeatedly.
2) The degree to which political differences in Israel pervaded everything and the degree of internecine hatred engendered.
3) The urgency accompanying many developments in Israeli politics.
Re #1, there might be value in comparing Israel to pre-1800 US, where constitutional arrangements had not been adequately tested, and when the role of judicial review had not been defined.
Re #2, the American 1850's--congressmen almost beating their colleagues to death on the Senate floor! Can one avoid considering how close Israel came to civil war in late 1940s?
Last week I read Orit Rozin's Hovat ha-Ahava ha-Kasha (English=Rise of Individualism in 1950s Israel), about early 1950's austerity policy, its links to mass immigration, the electoral consequences and the Ashkenazi contempt for the new immigrants that deterred mass immigration.
Confronting these questions is painful. I don't know how one can introduce them to 8th graders. At the same time, these are historical crises that continue to affect us today.