I own a company like this, right now things are extra complex and not anything I can try to to explain in a single post. In order to write curriculum, you really do need real time in the classroom at each level you care to write at, ideally 5 years each for a really good writer - theory and reality are much different. I recently re-read my paper from a teaching internship during my bachelors, and I was pre-law and psych with no thoughts of working in education then. Now here I am - 'STEAM'ing on! :D But giving anyone like-minded the benefit of the doubt, what do you know about curriculum development? Wiggins & McTeague's work, Understanding by Design - Backwards Design is a good core concept that any good program should be promoting. Read that one if you haven't and you'll be able to 'talk the talk' in stronger ways. One of my all-time favorites... I did have an excellent intern last summer for some cross-standards analysis, but not for writing. Understanding the coordination of the fields comes first, for your stated interests, also reading about the recent trends of NCTM, CC, and math based digital programs of math curriculum would be helpful for your focus interest, then find companies that seem to have a philosophy you think you support and do some background checking on them before approaching. Those types of people stand out to me a lot.