About MathLessons.com

In short

MathLessons.com publishes free, standards-aligned math lessons for US students, teachers and parents. Every one explains why a method works, walks through examples, and gives practice problems with full solutions. There are 63 lessons so far, each tagged to the Common Core standards it teaches and showing the full official wording of every one. They are written and edited by one named person, Cristian-Ovidiu Marin.

Who writes it

Cristian-Ovidiu Marin — BSc Computer Science, Titu Maiorescu University · software engineer since 2012

Background

BSc in Computer Science from Titu Maiorescu University, Bucharest.

Software engineer since 2012 — game AI at FUN Labs, then gameplay programming at Gameloft, both in C++. Since 2019, owner of FreezeNova, a free browser-games platform used by around 20 million people a year.

Why games and mathematics go together

Game programming is applied mathematics with a deadline. Coordinate geometry, vectors, trigonometry and linear algebra are the working material — how a character moves, where a camera points, whether two objects collide — rather than topics to revise for an exam.

That is the direct line between the day job and this site: an explanation is only finished when someone can use it.

Role on this site

Cristian chooses what gets covered, writes and edits every lesson before it goes live, and stands behind everything published here.

Corrections go to [email protected].

Full profile and work history.

How lessons are checked

Before a lesson is published, all of the following have to pass.

  • Standards come from the source. All 509 Common Core standards on this site were ingested from the official Common Core document rather than retyped, so each lesson shows a standard's exact wording rather than a paraphrase of it.
  • Every worked example is checked by hand. Every practice problem carries its full solution, worked line by line, so you can see where an answer comes from and check your own steps against it.
  • Every page is verified on each build. Every formula is confirmed to render, every diagram to carry a description for screen readers, every cross-reference to resolve, and every value in a figure to fall inside its own axes.
  • Reading level is measured, not assumed. Each lesson is scored against the grade it targets and written to land at that level.

Every lesson on the site has passed all four.

Corrections

Spotted something? Write to [email protected] with the page and what you saw. Mail is read by a person, and a correction is made at the source, so one fix reaches every page that uses the point. The page's "last updated" date changes with it.

How it is paid for

By advertising. Everything is free, there is no signup, and nothing is held back behind a paywall. Because the site is written for school-age readers, ads are configured for a child-directed audience — see theprivacy policy for what that means.