APES
Free-Response Strategy

Decode the command verbs.

APES has only 3 FRQs but they're heavily structured: each sub-part is one or two points and graded independently. Most lost points come from misreading the verb or skipping units on a calculation.

The three FRQ types

One of each appears on every exam. Plan your time: ~22–23 minutes per FRQ.

FRQWhat it asks
Q1 · Design an InvestigationHypothesis · IV/DV/controlled variables · procedure · expected results · interpret a conclusion.
Q2 · Analyze Problem & Propose SolutionDescribe the environmental problem · explain causes & effects · propose & defend a specific solution.
Q3 · Analyze with CalculationsSame as Q2 plus multi-step quantitative work. Show every unit.

The verb list

IDENTIFY

What it means: Name or list — usually one word or short phrase.

How to score: No explanation needed. One concise answer.

Example: "Identify the limiting nutrient in most freshwater ecosystems." → "Phosphorus."

DESCRIBE

What it means: Provide observable details or characteristics.

How to score: Answer "what does it look like?" — features, structures, observations. No reasoning required.

Example: "Describe the structure of an age-structure pyramid for a rapidly growing nation." → wide base, narrow top, shows many young people.

EXPLAIN

What it means: Provide reasoning, mechanism, cause-and-effect.

How to score: Answer "how" and "why" — every claim needs a because. The most-missed verb.

Example: "Explain why CFCs deplete stratospheric ozone." → UV cleaves CFC, releases Cl, Cl reacts with O₃ catalytically, one Cl destroys ~100,000 O₃.

JUSTIFY

What it means: Use evidence or logic to support a claim.

How to score: Connect data or known mechanisms to your conclusion. "This is supported by …"

Example: "Justify the claim that wind power has a lower carbon footprint than coal." → cite that wind has near-zero operational emissions vs. ~1 kg CO₂/kWh for coal.

CALCULATE

What it means: Do the math; show all dimensional analysis.

How to score: Show formula → substituted values with units → arithmetic → final answer with units. Lose units anywhere = lose the answer point. APES grading rewards the setup line even if arithmetic stumbles.

Example: "Calculate annual energy use of a 60 W bulb running 5 hr/day." → 60 W × 5 hr/day × 365 day/yr × (1 kWh / 1000 Wh) = 109.5 kWh/yr.

MAKE A CLAIM

What it means: State a specific position.

How to score: One concise sentence. Avoid hedging — "I claim that …" is fine.

PROPOSE A SOLUTION

What it means: Suggest a specific, realistic action with reasoning.

How to score: Be SPECIFIC. Name a policy / technology / behavior. Tie to the cause. "Plant trees" is weak; "Implement riparian buffer zones along the Mississippi watershed to absorb fertilizer runoff before it reaches the Gulf" earns the point.

Example: "Propose a solution to reduce eutrophication in Chesapeake Bay." → require buffer strips, ban phosphate detergents, regulate animal feeding operations.

PREDICT

What it means: State a likely outcome based on the given information.

How to score: Pair with reasoning if asked ("predict and explain"). Use future tense.

Example: "Predict the effect of ocean warming on coral reefs." → bleaching as zooxanthellae are expelled, reduced reef calcification, biodiversity loss.

COMPARE / CONTRAST

What it means: Note similarities and/or differences.

How to score: Address BOTH items in each comparison point. Use comparison words: "more than," "unlike," "both."

Example: "Compare exponential and logistic growth." → both describe pop. growth; exponential is unconstrained (J-curve), logistic plateaus at K (S-curve).

Writing tips

  • Match verb depth. "Identify" needs one phrase; "Explain" needs at least one sentence with mechanism.
  • ALWAYS include UNITS on every calculation — APES graders strip the answer point if units are missing.
  • Show all dimensional analysis with clear unit cancellation. Even if you can do it mentally, write it out — graders only score what they see.
  • Each sub-question (a), (b), (c) is graded independently — label your answers and answer each clearly.
  • Use specific examples (real species, real places, real laws). "Many animals die" earns 0; "salmon populations decline due to elevated water temperatures" earns the point.
  • Answer ALL THREE FRQs even if rushed — partial credit on all three beats perfect on two.
  • Don't over-write. Verbose hedging can introduce errors that contradict correct points (Earned-Point-Lost-on-Contradiction is real).
  • Use the language of the prompt. If asked about "an environmental problem," explicitly NAME it.
1. Write the formula or starting quantity with units
2. Multiply by conversion factors so unwanted units cancel
3. Show every step
4. Box the final answer WITH UNITS

Example:
  500 tons × (2000 lb / ton) × (1 kg / 2.2 lb) = 4.55 × 10⁵ kg