CK-12: A Learning Resource Collection

October 24, 2025

An adult woman watches as a young boy uses a tablet.

Today we are going to learn about a free resource called CK-12. This website is always free, and it has a huge collection of learning resources for parents, teachers, and students. The content on the website is aligned to the U.S. curriculum, but there’s so many accessible resources and learning materials that it still deserves some time in the spotlight.

First, when you navigate to the websites home page, you’ll be greeted by an AI tutor named Flexi who can answer virtually any question. This speech-to-text-friendly tool allows users to input drawn or typed equations, pictures, and it even features a built-in math keyboard.

From there, you can navigate to the top menu of the website to discover some of the resources that are available. In terms of subjects, there’s a lot to choose from. There’s a variety of Math subjects from Grade 1 to Algebra, Social Studies, Science, English, Adult Education, and more. And, within each subject area, there are lots of options in how that content is presented, from highly interactive to more conventional materials.

A screenshot of the CK12 app, displaying a math lesson.

They’ve also created a variety of unique learning tools. For example, there’s Flexlets, which are basically condensed, interactive textbooks that focus on the essentials of a given subject. They also provide a tool called a PLIX (Play, Learn, Interact, Explore) which is an interactive quiz/learning tool that focuses on a variety of math and science subjects. In addition to that, CK-12 provides Study Guides, Simulations, Webinars, and more.

The website also does a great job in making its content accessible. The learning materials are multi-modal, which is great for supporting a wide variety of learning styles. They also include image descriptions for screen readers, and their FlexBooks offer a variety of settings and reading modes designed for individuals with print impairments. And, because their materials are open-sourced, they can be configured and customized to each student’s specific needs.

CK-12 is available for free on PC, iOS, Android, Chrome, and WhatsApp. To learn more, click here (new window).

This post originally appeared on the AT Help Desk (new window) website.