Explain the mechanics of primary and general elections, how the Electoral College selects the president, and the major issues in campaign finance.
Choosing a president actually involves two elections. First, each party selects its nominee through primary elections and caucuses held state by state (open primaries let any registered voter participate; closed primaries limit voting to registered party members), culminating in a national convention where delegates formally nominate a candidate. Then, in the general election, voters in each state do not directly elect the president -- they select a slate of electors pledged to a candidate, together forming the Electoral College: 538 electors total (one for each of the 435 House seats and 100 Senate seats, plus three for Washington, D.C.), requiring 270 to win. Most states award all of their electoral votes to whichever candidate wins that state's popular vote, a winner-take-all system (Maine and Nebraska instead split electors by congressional district).
Because of the state-by-state, largely winner-take-all structure, a candidate can win the national popular vote yet lose the Electoral College, as happened in 2000 and 2016 (and, under a somewhat different process, in the disputed 1876 and 1888 elections). Supporters of the Electoral College argue it forces candidates to build broad, multi-regional coalitions rather than simply maximizing votes in the largest cities, and that it protects smaller states from being ignored entirely; critics argue it can override the national popular will and that campaigns effectively ignore most "safe" states to focus almost entirely on a handful of closely contested ones, a genuine, ongoing reform debate, including a modern effort called the National Popular Vote Interstate Compact. Campaigns are funded through a mix of individual donations (subject to legal contribution limits), party committees, and political action committees (PACs). In Citizens United v. FEC (2010), the Supreme Court ruled that corporations and unions have a First Amendment right to spend unlimited money independently (not coordinated with a candidate) on political advocacy, leading to the rise of "Super PACs." Supporters of that ruling frame independent political spending as protected free speech and association; critics argue it lets wealthy donors and organizations exert outsized influence on elections -- both positions have serious, sustained support, and the debate remains very much alive today.
Mastery looks like: They can explain the primary-to-general election sequence, describe how the Electoral College works including its winner-take-all feature in most states, and explain the Citizens United ruling along with arguments on both sides of that debate.
Common stumbles: Assuming citizens directly elect the president by national popular vote, or assuming a landslide win in one state produces more electoral votes than a narrow one.