Methodology

1. Spaced repetition for vocabulary and missed questions, using the SM-2 algorithm (the basis of Anki). Reviews due at 1, 3, 7, 14, 30+ days based on rating.
2. Interleaved practice in the Daily Challenge: 5 reading + 5 math, mixed. Research shows interleaving yields ~77% retention vs. ~38% for blocked practice at 24 hours.
3. Mandatory error analysis: every wrong answer is categorized (didn't know concept, misread, ran out of time, arithmetic slip, wrong strategy, guessed). Pattern visualization shows the dominant mistake type.
4. IRT-lite mastery scoring: easy/medium/hard questions weighted 1.0/1.5/2.5. A topic isn't mastered until the student handles hard questions reliably.
5. Realistic mock conditions: 60-minute timer, 70 questions in two sections (40 Reading + 30 Math), no calculator, navigation panel, flag-for-review, auto-submit on timeout.

The choices above are not invented; they come from cognitive science literature on retention and skill acquisition. Selected references:

• SuperMemo SM-2 algorithm (Wozniak, 1990) — the basis of every modern spaced-repetition system.
• Rohrer & Taylor (2007) on interleaved practice in mathematics.
• Roediger & Karpicke (2006) on the testing effect (retrieval practice).
• Item Response Theory (Lord, 1980) for difficulty-weighted scoring.
• Self-Determination Theory (Ryan & Deci, 2000) for our streak/freeze mechanic and mastery-tied (not vanity) achievements.

CPS does not publish official HSAT items, and we do not have access to retired test items. Our practice questions are:

• Original CC0 questions written to mirror HSAT structure and difficulty.
• Adapted from public-domain state assessments aligned to the same 8th-grade Common Core standards: NYSED Grade 8 ELA & Math, Massachusetts MCAS, Illinois IAR, Smarter Balanced.

Each question carries a source and license field visible in the explanation. We claim our practice mirrors the real test in format and difficulty distribution; we do not claim it shares actual content.

• We do not use leaked or retired HSAT items. There aren't any publicly available; if there were, using them would be unethical.
• We do not use shallow gamification (XP bars, badges for opening the app). 8th-graders see through that.
• We do not claim a guaranteed score. Score depends on practice consistency, baseline ability, and test-day variance.
• We do not collect any data on the server. We have no idea who uses the app or how.
• We do not advertise. There are no third-party scripts in the app — Lighthouse confirms zero trackers.

The 900-point projection in the score report uses the public CPS formula:

• HSAT raw score → estimated percentile (smooth curve calibrated to published cutoff data).
• Percentile × 2.2727 = HSAT points (max 225 per section, 450 total).
• + 7th-grade core grades: A = 112.5 pts, B = 75, C = 38, D/F = 0; max 450.
• Total: 900. Top SEHS programs target ~860+.

The percentile curve is our best estimate. CPS does not publish the official raw→percentile table. Our projection is an educational estimate, not a guarantee. We label it as such throughout the app.

If you spot a question with an incorrect answer or explanation, or if CPS publishes new information about the HSAT format, please open an issue or contact us. We update the question bank in batches; bug fixes ship within a few days when reported.