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🏆Intro to English Grammar

Active vs. Passive Voice

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Why This Matters

Voice is one of the most tested grammar concepts because it directly affects clarity, emphasis, and tone—three things the AP exam expects you to analyze and control. You're being tested on your ability to recognize how writers make strategic choices: shifting responsibility, emphasizing results over actors, or creating directness and energy. Understanding voice isn't just about identifying sentence patterns; it's about understanding rhetorical effect.

The good news? Once you grasp the underlying mechanics, voice questions become predictable. Don't just memorize that active voice has the subject "doing" something—know why a writer might choose one voice over another and what effect that choice creates. This is the difference between a surface-level answer and one that earns full credit.


Understanding the Basic Structures

Before you can analyze voice strategically, you need to recognize it instantly. These foundational concepts show you how each voice is built grammatically.

Active Voice Structure

  • Subject performs the action—the doer comes first, creating immediate clarity about who or what is responsible
  • Subject-Verb-Object order follows English's natural sentence flow, making sentences feel direct and energetic
  • No "to be" + past participle construction—the main verb carries the action alone, keeping sentences lean

Passive Voice Structure

  • Subject receives the action—the thing being acted upon takes the spotlight, shifting focus away from the doer
  • "To be" verb + past participle forms the core construction (is written, was discovered, has been completed)
  • Agent is optional—the doer may appear after "by" or be omitted entirely, which can create ambiguity or objectivity

The Agent in Passive Constructions

  • "By" introduces the agent—when present, this phrase reveals who performed the action (The report was written by the committee)
  • Omitted agents occur when the doer is unknown, obvious, or deliberately hidden—a key rhetorical move
  • Identifying the agent is essential for understanding responsibility and for converting between voices

Compare: "The committee wrote the report" vs. "The report was written by the committee"—both convey the same information, but active emphasizes who did it while passive emphasizes what was done. If an FRQ asks about emphasis or focus, this distinction is your answer.


Strategic Uses of Each Voice

Knowing when to use each voice is where grammar meets rhetoric. These aren't arbitrary rules—they're tools for achieving specific effects.

When Active Voice Works Best

  • Clarity and directness make active voice the default for most academic and professional writing
  • Engaging readers happens naturally when sentences have clear actors taking clear actions
  • Strong, confident tone emerges from active constructions—compare "Mistakes were made" to "I made a mistake"

When Passive Voice Works Best

  • Unknown or irrelevant doer justifies passive—The pyramids were built thousands of years ago (we don't know exactly who)
  • Scientific and technical writing uses passive to emphasize procedures and results over researchers (The solution was heated to 100°C)
  • Objectivity and formality increase with passive voice, which is why legal and bureaucratic documents favor it

Compare: "Scientists discovered the vaccine" vs. "The vaccine was discovered"—active credits the scientists, while passive emphasizes the discovery itself. Use this example if asked about tone or emphasis in scientific contexts.


Converting Between Voices

The ability to transform sentences between voices proves you understand the mechanics—and it's a common test question. The key is tracking what moves where.

Active to Passive Conversion

  • Object becomes subject—identify what's receiving the action and move it to the front of the sentence
  • Add "to be" + past participle—match the tense of the original verb (wrotewas written, will finishwill be finished)
  • Original subject becomes agent—place it after "by" or omit it if context makes the doer clear

Passive to Active Conversion

  • Agent becomes subject—find the "by" phrase (or infer the doer) and move it to the front
  • Remove "to be" construction—restore the main verb to its active form, matching the original tense
  • Former subject becomes object—it now receives the action at the end of the sentence

Compare: Converting "The ball was thrown by Maria" to "Maria threw the ball" requires three moves: agent → subject, remove "was," object → end. Practice this process until it's automatic—timed sections reward speed.


Common Errors and Pitfalls

These mistakes cost students points. Recognizing them in your own writing—and in passages you analyze—demonstrates mastery.

Overusing Passive Voice

  • Vague, weak writing results from too many passive constructions strung together—readers lose track of who's doing what
  • Diluted impact occurs when passive hides strong actors behind weak verbs (A decision was reached vs. The board decided)
  • Wordiness is a side effect—passive sentences typically use more words to convey the same information

Misidentifying Voice

  • "To be" doesn't automatically mean passiveShe is running is active (progressive tense), not passive
  • Past participles need "to be"The window broke is active; The window was broken is passive
  • Look for the doer-action relationship—ask "Who or what is performing the verb's action?"

Compare: "The glass was broken" (passive—something broke it) vs. "The glass broke" (active—the glass performed the breaking, even if accidentally). This distinction trips up many students on identification questions.


Quick Reference Table

ConceptBest Examples
Active voice markersSubject-Verb-Object order, no "to be" + participle
Passive voice markers"To be" + past participle, optional "by" phrase
Use active forClarity, directness, engaging tone, strong statements
Use passive forUnknown doer, scientific writing, objectivity, emphasizing results
Active → PassiveObject → subject, add "to be" + participle, subject → "by" phrase
Passive → ActiveAgent → subject, remove "to be," former subject → object
Common passive errorOveruse creating vague, wordy, or evasive writing
Tricky identificationProgressive tense (is running) is NOT passive

Self-Check Questions

  1. What two structural elements signal that a sentence is in passive voice?

  2. Compare "The experiment was conducted" and "Dr. Lee conducted the experiment"—which emphasizes the action, which emphasizes the actor, and when might each be appropriate?

  3. Why might a politician say "Mistakes were made" instead of "I made mistakes," and what effect does this voice choice create?

  4. Convert this passive sentence to active: "The novel was written by Toni Morrison in 1987." What changes, and what stays the same?

  5. A student writes: "The ball is bouncing" and labels it passive because it contains "is." What's wrong with this identification, and how would you explain the difference?