Attribution Guidelines


Giving us credit when you use our content and technology is not just important for legal reasons. When you provide attribution to CK-12 Foundation, you support the ability of our non-profit organization to make great educational experiences available to students around the world.

CK-12 Foundation is licensed under Creative Commons AttributionNonCommercial 3.0 Unported (CC BY-NC 3.0)Our Creative Commons License welcomes you to use our content and technology when you give us attribution.

If you have any questions about our policies, contact us at

Reproducing Content

When you copy CK-12 content to any kind of print document, include one of the attributions below.

1. For online distribution:

Licensed under CK-12 Foundation is licensed under Creative Commons AttributionNonCommercial 3.0 Unported (CC BY-NC 3.0) • Terms of Use • Attribution

Google Crawling & Indexing of Content

If you display CK-12 content on your website, we require that you include the following HTML tag on all your website pages that contain CK-12 content, so as to block Google from crawling and indexing CK-12 content displayed on your website:

There are two options on adding the noindex rule to your website pages.

Option A: Add a noindex rule using a meta tag on each page.
<meta> tag
To prevent most search engine web crawlers from indexing a page on your site, place the following meta tag into the section of your page:

<meta name="robots" content="noindex">


Option B: Add a noindex rule using an HTTP response header.
HTTP response header
Instead of a meta tag, you can also return an X-Robots-Tag header with a value of either noindex or none in your response. Here’s an example of an HTTP response with an X-Robots-Tag instructing crawlers not to index a page:

HTTP/1.1 200 OK
X-Robots-Tag: noindex

2. For print distribution:


Right-click to download the image above. Be sure to include the attribution even if you modified the content that was copied.

3. Embedding Content
We encourage you to embed CK-12 assessment content into your HTML web pages by using our embed codes.

Attribution to CK-12 automatically appears on the content. There’s nothing for you to do!