Final answer:
National conventions elect a Vice President nominee in addition to a presidential candidate. Positions like Secretary of State, Speaker of the House, or Supreme Court Justices are not elected at these conventions. The Vice President is usually chosen by the presidential nominee and announced during the convention.
Step-by-step explanation:
Other than nominating a candidate for president at national conventions, the parties also elect a nominee for Vice President. The roles of Secretary of State, Speaker of the House, and Supreme Court Justices are not selected during the national conventions. It is during these conventions that the chosen presidential candidate often announces their running mate for Vice President, who, like the presidential nominee, has usually been determined before the convention due to the results of the primary elections.
Additionally, at the national convention, delegates will confirm the primary election results, debate and vote on the party's platform, and engage in networking and promotional activities. However, the national convention does not elect positions such as Secretary of State, Speaker of the House, or Supreme Court Justices as these positions are not part of the convention's agenda.