Learn to umpire baseball by mastering the NFHS high-school rulebook and how it applies on the field — the foundation of the state high-school umpiring exams. Master the strike zone and what makes a legal catch, fair versus foul, the count and the uncaught third strike, force plays versus tag plays, the infield fly rule (its conditions and why it exists), balks (an immediate dead ball in NFHS — a key difference from pro rules), obstruction (on a fielder) versus interference (by the offense), catcher's interference, tagging up and appeal plays, base awards on dead balls, and the NFHS specifics like the designated hitter and the courtesy runner. Each question teaches the rule, names the classic confusion (obstruction versus interference, force versus tag, fair versus foul), and ends with a portable cue. Authored from the public NFHS baseball rules book, case book, and points of emphasis using original questions — never real exam items — and stamped to the NFHS high-school code, which changes yearly (pro OBR, NCAA, and Little League rules differ — for example, NFHS balks are an immediate dead ball). Keentune is independent study practice, not affiliated with or endorsed by the NFHS, MLB, the NCAA, or Little League, and does not guarantee a pass. Educational only — how the rules work, not umpiring advice for a specific game.