I understand that FlexBooks are free, or open source. Is the software that supports the FlexBooks open source, too? Our mission is to provide all our materials for free under the Creative Commons Attribution/Non-Commercial/Share Alike 3.0 Unported (CC-BY-NC-SA) License. For more information on the CC-BY-NC-SA license, see the selection of this FAQ about the content of FlexBooks, or visit the following URL, http://creativecommons.org/licenses/by-nc-sa/3.0/. Our CK-12 system for FlexBooks is not yet geared to be a separate open source project.