Coding & Math Fundamentals: The Free Curriculum
AI tools amplify what you understand. They don’t replace it. A student who knows why the code works directs AI tools ten times better than one who doesn’t. This is our verified list of the best genuinely-free places to build those foundations, in both tracks: math (the logic under everything) and coding/CS. We checked every link and, more importantly, every “free” claim, because this space is full of freemium traps dressed up as free resources. The biggest one we rejected is at the bottom.
Math
Khan Academy — Math
The complete K-through-college math ladder (arithmetic to AP Calculus and Statistics), with videos, mastery-based practice, and instant feedback. The single best structured spine for filling gaps or getting ahead.
What’s free: Everything, always: nonprofit, no freemium tier exists.
Ages 10–18, all levels Math
Art of Problem Solving (AoPS)
The home of competition math (AMC, MATHCOUNTS, olympiad culture), where mathematically ambitious teens go beyond school math.
What’s free: Alcumus (adaptive problem trainer), instructional videos, forums, and practice contests are free. The famous online classes and textbooks cost money.
Ages 12–18, strong/motivated students Math
3Blue1Brown
Grant Sanderson's animated visual math: Essence of Calculus, Essence of Linear Algebra, and the neural-network series that bridges straight into how AI actually works. It builds intuition no textbook matches.
What’s free: All lessons and videos (Patreon is early-access only, not a paywall).
Ages 14–18 (younger for the curious) Both
Project Euler
Nearly 1,000 problems that require both mathematical thinking and code to solve, the canonical bridge between the two tracks.
What’s free: Completely free, no paid anything.
Ages 14–18, with some programming Both
Desmos
The browser graphing calculator that's become the classroom and standardized-test standard: instant, beautiful, zero-install.
What’s free: All calculators free (paid products target schools, not students).
Ages 10–18, all levels Math
GeoGebra
Free graphing, geometry, 3D, and scientific tools plus thousands of interactive community applets, stronger than Desmos for geometry constructions and 3D.
What’s free: All tools free.
Ages 10–18, all levels Math
Paul's Online Math Notes
A Lamar University professor's famously clear notes for algebra through Calc III and differential equations, with worked practice problems and downloadable cheat sheets.
What’s free: Everything, including all the PDFs.
Ages 15–19, ideal for AP and early college Math
BetterExplained
"Aha-first" essays on e, π, logarithms, calculus, and trig. The fix for "I can compute it but I don't get it."
What’s free: All articles and the online calculus course (optional ebook is paid).
Ages 13–19 Math
Note: An evergreen reference library, not an active blog. Treat it as a place to look things up, not a course to follow.
Coding & computer science
Khan Academy — Intro to Computer Science: Python
The new Python-first intro course with an in-browser editor that even works on tablets. The gentlest serious on-ramp on this list.
What’s free: 100% free (skip their older legacy JavaScript courses; this is the one to start with).
Ages 11–15, absolute beginners Coding
Harvard CS50x
Harvard's legendary intro to computer science: computational thinking, C, Python, SQL, web. The gold-standard first serious CS course.
What’s free: All material and problem sets, plus a free CS50 certificate for completing the work (only the edX verified certificate costs money).
Ages 15–19, beginner-friendly but rigorous Coding
Automate the Boring Stuff with Python
Al Sweigart's practical Python book: spreadsheets, files, web scraping, automation. Teens see code doing genuinely useful things fast.
What’s free: The entire current (3rd) edition free online under Creative Commons.
Ages 13–19 Coding
Eloquent JavaScript
The standard free JavaScript book (4th edition), with in-browser sandboxes and exercises, more intellectually serious than typical web tutorials.
What’s free: Full book online plus free PDF/EPUB downloads; only the paperback is paid.
Ages 14–18, beginners with patience Coding
freeCodeCamp
Project-based certifications in web development, JavaScript, Python, and data science, roughly 300 hours each, earned by building real projects in the browser.
What’s free: "Every aspect… 100% free. The courses, the projects, even the certifications." Donor-supported nonprofit.
Ages 13–19 Coding
Exercism
8,500+ exercises across 83 languages, with free human mentoring: volunteers actually review your code, which nothing else on this list offers.
What’s free: "100% free, forever" (nonprofit); the paid tier is a donor thank-you, not a feature gate.
Ages 13–19, once you know basic syntax Coding
Codewars
Gamified "kata" challenges with martial-arts ranks; after each solve you see other people's solutions. That compare-and-learn loop is the real value.
What’s free: The kata library, ranks, and leaderboards (the paid subscription is ignorable extras).
Ages 13–19 Coding
MIT OpenCourseWare — Intro to CS with Python (6.100L)
The actual MIT intro course: full lecture videos, notes, and problem sets, explicitly aimed at students with little to no programming experience.
What’s free: Everything, no strings, no account.
Ages 15–19, strong students (it moves fast) Coding
MDN Learn Web Development
Mozilla's structured beginner curriculum for HTML, CSS, and JavaScript, plus the industry-reference docs students will use for the rest of their careers.
What’s free: Entirely free, no account, no ads, no upsold certificates.
Ages 13–19 Coding
CS Unplugged
Computer science without computers: cards, string, and running around to teach binary, sorting, and error correction.
What’s free: All printables and lessons, Creative Commons.
Ages 11–13 (it's primary-leaning) Coding
CS Field Guide
An interactive online CS textbook written for high schoolers: algorithms, data representation, encryption, AI, human-computer interaction.
What’s free: Open source, fully free.
Ages 14–18, the natural step up from CS Unplugged Coding
roadmap.sh
Community-built visual roadmaps (frontend, backend, Python, AI engineer…) that answer "what should I learn next?" It's a map, not a course.
What’s free: All roadmaps and guides.
Ages 14–18, once you've started coding Coding
LeetCode (free tier)
Interview-style algorithm and data-structure problems. Only relevant for older teens targeting competitive programming or CS-admissions portfolios.
What’s free: 1,600+ of its problems with discussion forums; Premium is for job-hunters, teens don't need it.
Ages 16–19, advanced Both
YouTube worth a teen’s time (math edition)
For coding YouTube (freeCodeCamp, Fireship, Traversy Media, Tech With Tim), see our AI-assisted coding page.
Numberphile
Real mathematicians telling weird, delightful number stories. Zero prerequisites: pure curiosity fuel.
What’s free: Free; very active (uploading weekly as of July 2026).
Ages 10–18 Math
Mathologer
Deep visual proofs: why formulas are true, not just what they are. More rigorous than Numberphile.
What’s free: Free; active at a slow cadence (a few videos a year).
Ages 14–18 Math
blackpenredpen
Calculus and algebra problems worked marker-on-whiteboard in real time, the closest thing to a free calc tutor, ideal for AP students.
What’s free: Free; very active.
Ages 15–19 Math
What we checked and rejected (July 2026)
- Brilliant: heavily advertised as if free, but the free tier is course previews and a few daily “keys” that run out fast; actually completing any course requires Premium at roughly $28/month. A classic freemium trap, so we don’t list it as a free resource.
- W3Schools: not paywalled, but passed over deliberately. It’s ad-supported, sells paid certificates of little value, and its reference quality is a tier below MDN, which covers the same ground with a real curriculum.
- Khan Academy’s legacy JavaScript courses: still online, but superseded by their new Python intro; start there instead.