HESI A2 Last-Minute Study Guide: What to Review the Night Before Your Exam

Your Exam Is Tomorrow — Here's How to Make Every Minute Count

First, take a deep breath. If you're reading this the night before your HESI A2 exam, you're not alone — thousands of nursing students find themselves in the same position every year. The good news? Strategic last-minute review can genuinely boost your score by 5-10 points if you focus on the right material.

This guide isn't about trying to learn everything from scratch. It's about reinforcing what you already know, filling in critical gaps with the highest-yield content, and walking into your exam with confidence. We've identified the most commonly tested concepts across all HESI A2 sections so you can prioritize what matters most.

Mathematics: The Must-Know Formulas

The HESI A2 Math section is one of the most predictable — the same formula types appear on nearly every exam. Memorize these and you'll cover roughly 70% of math questions:

Conversion Formulas (Highest Priority)

• Metric to metric: King Henry Died By Drinking Chocolate Milk (Kilo, Hecto, Deka, Base, Deci, Centi, Milli) — move the decimal point for each step
• Temperature: °F = (°C × 9/5) + 32 | °C = (°F - 32) × 5/9
• Weight: 1 kg = 2.2 lbs | 1 oz = 28.35 g
• Volume: 1 L = 1000 mL | 1 cup = 240 mL | 1 tsp = 5 mL
• Length: 1 inch = 2.54 cm | 1 mile = 1.6 km

Fraction & Percentage Rules

• Fraction to decimal: Divide numerator by denominator
• Decimal to percent: Multiply by 100
• Finding a percentage: Part ÷ Whole × 100
• Ratio and proportion: Cross-multiply to solve (a/b = c/d → ad = bc)

Dosage Calculation (Appears on Every Exam)

Desired ÷ Have × Vehicle = Amount to give

Example: Doctor orders 500 mg. You have 250 mg/tablet. → 500 ÷ 250 × 1 = 2 tablets

Anatomy & Physiology: The Top 5 Systems to Review

A&P is a massive subject, but HESI A2 questions cluster around specific systems. Here's what to prioritize:

1. Cardiovascular System (Most Tested)

• Blood flow path: Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium → Left ventricle → Aorta
• Heart valves: Tricuspid (right AV), Bicuspid/Mitral (left AV), Pulmonary semilunar, Aortic semilunar
• Blood types: O is universal donor, AB is universal recipient
• Blood components: RBCs carry oxygen, WBCs fight infection, Platelets clot, Plasma is liquid

2. Respiratory System

• Gas exchange: Occurs at alveoli via diffusion
• Breathing: Diaphragm contracts (flattens) → lungs expand → air enters
• Key structures: Trachea → Bronchi → Bronchioles → Alveoli

3. Nervous System

• CNS: Brain + Spinal cord
• PNS: Everything else (somatic + autonomic)
• Autonomic: Sympathetic (fight or flight) vs. Parasympathetic (rest and digest)
• Neuron parts: Dendrite → Cell body → Axon → Axon terminal

4. Digestive System

• Order: Mouth → Esophagus → Stomach → Small intestine → Large intestine → Rectum
• Nutrient absorption: Primarily in the small intestine (villi increase surface area)
• Key organs: Liver (bile production), Pancreas (enzymes + insulin), Gallbladder (bile storage)

5. Endocrine System

• Insulin: Lowers blood sugar (pancreas)
• Glucagon: Raises blood sugar (pancreas)
• Thyroid hormones: T3 & T4 regulate metabolism
• Adrenal glands: Cortisol (stress) + Epinephrine (fight or flight)

Vocabulary: 30 Words That Appear Most Often

These high-frequency medical terms show up repeatedly on the HESI A2. Focus on these first:

Grammar: The 5 Rules They Always Test

The Grammar section is highly predictable. Master these five concepts:

1. Subject-Verb Agreement

Singular subjects take singular verbs. Watch for tricky phrases between subject and verb: "The group of students is studying" (not "are").

2. Comma Splices vs. Run-On Sentences

Two independent clauses need a period, semicolon, or conjunction — NOT just a comma. Wrong: "The patient felt better, she left." Right: "The patient felt better, so she left."

3. Commonly Confused Words

• Their/There/They're — possession/location/they are
• Affect/Effect — verb (to influence) / noun (result)
• Then/Than — time sequence / comparison
• Its/It's — possession / it is

4. Apostrophe Rules

Possessive nouns get apostrophes (nurse's, nurses'). Possessive pronouns do NOT (its, theirs, whose).

5. Sentence Structure

Know the difference between independent and dependent clauses. A dependent clause alone is a fragment: "Because the patient was discharged" needs an independent clause to be complete.

Reading Comprehension: Quick Strategy Refresher

You can't cram reading skills, but you CAN sharpen your approach:

• Read the questions FIRST — know what you're looking for before reading the passage
• Look for the main idea in the first and last sentences of each paragraph
• Eliminate extreme answers — words like "always," "never," and "all" are usually wrong
• Don't infer beyond the text — the answer must be supported by the passage, not outside knowledge
• For "author's purpose" questions: Is it to inform, persuade, entertain, or describe?

Chemistry: Essential Quick-Review Concepts

• pH scale: 0-6 acidic, 7 neutral, 8-14 basic/alkaline
• Atomic number = number of protons; Mass number = protons + neutrons
• Ionic bonds: Transfer of electrons (metals + nonmetals)
• Covalent bonds: Sharing of electrons (nonmetals + nonmetals)
• Exothermic: Releases energy | Endothermic: Absorbs energy
• Catalyst: Speeds up reaction without being consumed
• Molarity: Moles of solute ÷ Liters of solution
• Water: Universal solvent, high specific heat, polar molecule

Biology: Last-Minute High-Yield Topics

• Cell membrane: Phospholipid bilayer, selectively permeable
• Mitosis: PMAT (Prophase, Metaphase, Anaphase, Telophase) — produces 2 identical cells
• Meiosis: Produces 4 haploid gametes (sex cells) — introduces genetic variation
• DNA vs RNA: DNA is double-stranded (A-T, G-C); RNA is single-stranded (A-U, G-C)
• Dominant vs Recessive: Dominant allele masks recessive; both recessive needed for expression
• Photosynthesis: 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂
• Cellular respiration: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP

10 Test-Taking Strategies for Tomorrow

These strategies work regardless of how prepared you feel:

1. Answer every question. There is no penalty for guessing on the HESI A2.
2. Eliminate two wrong answers first. This gives you a 50/50 chance even when guessing.
3. Watch for "absolute" words. Options with "always," "never," or "all" are rarely correct.
4. Read ALL answer choices before selecting — the last option might be better.
5. Don't change your answer unless you're absolutely certain. First instinct is usually right.
6. Flag and move on. Don't spend more than 90 seconds on any single question.
7. Use dimensional analysis for all math conversion problems.
8. For vocabulary, break unfamiliar words into prefixes, roots, and suffixes.
9. In reading passages, look for transition words (however, therefore, in contrast) to find key information.
10. Watch your time. Aim for about 1 minute per question and check the clock every 15 questions.

The Night-Before Checklist

Beyond studying, these practical steps set you up for success:

What to Do Tonight

• ✅ Lay out everything you need: Valid photo ID, confirmation email/number, approved calculator (if allowed)
• ✅ Set TWO alarms — one on your phone and one backup
• ✅ Know your test center location and plan to arrive 30 minutes early
• ✅ Eat a balanced dinner — protein + complex carbs for sustained energy
• ✅ Stop studying 1 hour before bed — let your brain consolidate
• ✅ Sleep 7-8 hours minimum — sleep is when memory solidifies

What NOT to Do

• ❌ Don't try to learn new material from scratch
• ❌ Don't stay up past midnight studying
• ❌ Don't skip meals or rely on caffeine alone
• ❌ Don't review material that makes you anxious
• ❌ Don't doom-scroll nursing school forums

Morning of the Exam

• 🌅 Eat a protein-rich breakfast (eggs, yogurt, oatmeal — avoid sugar crashes)
• 🌅 Light caffeine is fine if it's part of your routine — don't overdo it
• 🌅 Quick 10-minute review of your weakest section's cheat sheet
• 🌅 Arrive 30 minutes early to settle in and reduce stress
• 🌅 Positive self-talk: You've prepared. You know this material. Trust your preparation.