Mental model
A line you can remember
Every lesson opens with one short, sticky phrase that captures the concept — easier to recall than any definition.
998 lessons · 5 subjects · North American K–12
North American K‑12 math and science, taught the way you’ll actually understand.
Sense of Study gives North American K–12 students direct answers to math, science, statistics, and CS concepts, then shows when to use each idea. Every lesson is built around one rule: teach the recognition problem, not just the definition.
Free to read every lesson and try every practice problem. No account needed.
── Tutor replacement
Your kid's tutor on call — for the price of a coffee a month.
Replaces 90%+ of what an off-campus math tutor does: lessons that teach recognition, 20-question practice packs graded server-side, and a parent report on /family that shows whether your kid is mastering material and keeping the standing slots you set.
You spend $1,600/year on tutoring.
Sense of Study Family is $99/year for up to 5 children
— that's 16× cheaper, saving $1,501.
Math tutors do things we don't — diagnosing learning disabilities, building human rapport, reading body language. If your child needs those, no software replaces them. For the explanation, pacing, and progress-tracking parts, we cover ~90% of what a tutor does at <5% of the price.
The contract: mastery, cadence, visibility.
- Mastery — 18+/20 on a concept's practice pack.
- Cadence — you pick two standing slots a week; we score whether they happen.
- Visibility — a one-glance report tells you in 5 seconds how your kid is doing.
If we don't keep this contract, you'll see it on /family before you see it on a report card.
What makes a lesson different
Three sections most textbooks skip — on every lesson page.
Recognition checklist
Know when to use it
Not just what a concept means, but which clues in a problem tell you it applies. The single most asked-for thing students miss in textbooks.
Comparison table
Tell apart the look-alikes
Side-by-side rows that disambiguate this concept from the 1–2 it gets confused with. Independent vs dependent vs mutually exclusive, every page.
What's covered
998 lessons across five subjects.
Every concept on the site uses the same 13-section structure: quick answer, why it matters, intuition, recognition, comparison, formula, worked examples, mistakes, practice, learning path, and more.
998 lessons · 51,014 practice questions · every worked solution human-reviewed · built by a parent.
Why recognition-first works
Backed by decades of learning-science research.
Recognition over recall
"Students who can recognize when a concept applies outperform those who can only define it."— Concept-mastery research, applied across STEM education.
Built-in retrieval
"Spaced retrieval beats massed practice for long-term retention."— Roediger & Karpicke (2006). The testing effect.
Worked examples that teach the why
"Worked examples paired with explanations produce better transfer than examples alone."— Sweller (2010). Cognitive load theory.
Pricing
Every lesson free. One plan unlocks the worked solutions.
All 998 lessons and every practice question are free — including the final answer and first solution step. The Family plan unlocks every full worked solution, unlimited mastery checks, up to 5 kid profiles, and the parent dashboard.
See plans →