Does it actually work?

Everything below is computed and shown only on your device. Nothing is sent to a server — there are no accounts, no analytics, and no way for us to see your scores. Your progress view shows them to you.

• Pre/post diagnostic delta. The diagnostic is a fixed-form set of 20 questions covering every topic. Because the same items are re-used when you retake it, the change in your score reflects learning rather than which questions you happened to get. This is the cleanest single signal we have.
• Mock-score trajectory. Each full mock records a projected HSAT score; we show your first-to-latest change so you can see the trend across attempts.
• Re-mastery of missed questions. Questions you miss are rescheduled (spaced repetition). We track how many you later answer correctly — direct evidence that review is working.
• Difficulty-weighted accuracy. Because practice gets harder as you improve, raw percent-correct can fall while your ability rises. We weight harder questions more so the trend reflects real growth, not just question difficulty.

The app converts your raw mock results into a projected 900-point composite (HSAT 450 + 7th-grade grades 450), the same structure CPS uses for points-based Selective Enrollment admissions. We anchor that projection to publicly reported cutoffs so a projected score maps to a realistic admissions picture rather than an arbitrary number.

Cutoffs (of 900) are approximate, compiled from publicly reported data, and vary year to year. Treat them as guidance, not a promise.

Being honest about the limits is the whole point:

• No control group. We measure your change over time, not against a comparable student who didn't use the app. So we can show you improved on our instruments, not that the app alone caused it (school, other studying, and growing older all contribute).
• Our mocks aren't the real HSAT. They mirror its format and are calibrated to public cutoffs, but a projected score is an estimate, not your actual result.
• Self-selection. Students who keep practicing are already more motivated, which inflates any average gain among active users.

The strongest honest claim this design supports is: students who used the app improved by a measurable amount on a fixed diagnostic they took twice. That is genuinely useful — and rare among prep tools that just assert results.