concept of links: satellite image over Italy, blended with sphere of networked circles


6 Sites For Free Alternative Textbooks

(Excerpt from: Info from UW News – Posted by Erik Geiger on August 27, 2018)
Note: The original page is no longer online but an ARCHIVE exists

[…] Engineers, and other STEM majors will want to check out MIT Open Courseware.

A useful addition to this list is: LibreText -Biology:
For example: UC Davis Biological Sciences (BIS 2A) Introduction to Biology: Essentials of Life on Earth Winter 2018: Dr. Easlon

Open Culture

Free textbooks (aka open textbooks) written by knowledgable scholars are a relatively new phenomenon. Open Culture offers 200 Free Textbooks.

MIT Open Courseware

MIT OpenCourseWare is a web-based publication of virtually all MIT course content. OCW is open and available to the world and is a permanent MIT activity.

Textbook Revolution

Textbook Revolution is a student-run site dedicated to increasing the use of free educational materials by teachers and professors.


Wikibooks is an open-content textbooks collection that anyone can edit.

Project Gutenberg

Project Gutenberg offers over 56,000 free, public domain eBooks in multiple formats. Topics include English and international literature, foreign languages, history, mathematics, and language instruction.


OpenStax offers peer reviewed, open source textbooks are written by professional content developers who are experts in their fields.

Free Stock Photos, Videos

Stock photography is sometimes referred to as “Royalty Free” but that implies an up-font, one time purchase. The following are useful sources of free (no upfront cost) magnificent photographs, illustrations, vector art, and background looped videos.

Name link login required Notes
Pixabay no Free for commercial use No attribution required
Pexels no Legal Simplicity All photos and videos on Pexels can be downloaded and used for free.
Freepik yes/no attribution required **
Vecteezy no* attribution required **
Chamber of Commerce yes/no Meta search engine covering multiple sites


(*) limited to 5 downloads per day
(**) most require attrubution. Waved if registered.

I have used Pixabay the most, once in a while I found a more suited image in Pexels. Neither require a login to download, except for extremely high resolution or vector images. Vecteezy has many images, icons, illustrations, but not all are free. But unlike other sites there are choices for looped background videos, that are suited for broadcast or even a Zoom meeting. EDIT: Pixabay also has short animations: videos/search/3d/

The Chamber of Commerce link is in fact a “meta search engine” that searches in multiple web sites. Pixabay and Pexels are included. However, some of the other included web sites require a login account to download images. While the login is free, it is yet another account to handle…


Tool to compress photos:

Image Compressor:


Cheat sheets can be useful as a memory back-up. When I learned Latin, it was stressed that before looking into the lexicon, one should first try to retrieve the information from memory first. It may be there. Then, if needed, look into cheat sheet, which can sometimes be a challenge too given the information concentration. Cheat sheets come in various formats, which can sometimes be called quick reference guide instead.

Molecular graphics

RStudio / R

RStudio provides a large series of cheat sheets that encompass a wide range of subjects. The page is located at and covers R, python, R markdown and many specific R packages.


(Note: These are from web site that offers further cheatsheets that are more relevant to web development such as JavaScript, PHP or HTML.)