Get a 'tab group' add on, Simple Tab Groups for Firefox. There is something similar for Chrome but I don't know off the top of my head.
I have a different group for any 'context' I often return to (or even a dump of 'researching random thing I may one day come back to'). Then I have one window open and I switch between contexts as needed and pick up from where I left off.
Comparing to the answer I just looked up in the print version of the book (and double checking on google) the http://factfulnessquiz.com/ is incorrect on this point.
I have a different group for any 'context' I often return to (or even a dump of 'researching random thing I may one day come back to'). Then I have one window open and I switch between contexts as needed and pick up from where I left off.