Best Introductory Astronomy text so far, and I have been teaching astronomy to college students for 30 years in a planetarium at a community college. It uses the current technology (video and the web), it is inexpensive as an iBook text, and free as a PDF. It is comprehensive and can be adapted for a one or two semester course.

I have been learning so much from these openstax books, thank you so much for your work.

I have vision issues and like to increase font sizes. This iBook doesn’t seem to allow for that.