The way I see it, if the content is at all going to be approachable by children aged 11 and up, then that content needs to be well designed, typeset and proofre

The way I see it, if the content is at all going to be approachable by children aged 11 and up, then that content needs to be well designed, typeset and proofread. While writing an open source book for professionals, pointing them to a set of markdownfiles would suffice if the content is good enough. The idea is that the design and the content should facilitate children's learning as much as possible. I could definitely go the publisher route with this, but then the whole project will change characteristics and be less dynamic. Its not the open source code or project that is important in this project, its really the end result which is content that is easily approachable for the target audience.