what factors should consider whicle designing an digital textbook?

In order to design a digital text book, you should consider first the size of the book, then the number of pages. After that, you should have a text, an article or something like. It will be good if you have some photos or drawings to illustrate the book. Doesn't matter if you don't have them, but the text is essential. Then you must choice the software you want to use to designing the book. I think you can start using Word Office. You need to choice the type of letter to use, for example Arial, Helvetica, Verdana, Times or Garamond. Types of letters there are a lot, but these are classics. I recommend to use not more than three family types in one design. The size of titles should be 14 points and from the body text 10 points. You have to determinate the margins from your page and where you will put the number from it (mostly below outside). Another good software is Quark X Press or InDesign, although these are requiring knowledge.

Font must be good for appearance, then only the student can read more time. And the size adjustment facility also keep in it. We have to provide clear information on which topic we are going to publish a digital book. The student feels boring if there is only text, we have to place the colorful images which are related to our digital book. All the best!!!