Congratulations, we are halfway through our 'course' already! How do you feel? Today, we are focusing on the position of your reading material (and subsequently your posture).
Tilt your book up about 20 degrees (this slopes up about 4 inches in 12).
By doing this, you can usually work farther away than when you place the book flat on the desk.
I found this picture when I searched for book stands and I think it shows very nicely how your posture changes completely when you work with a sloped book.
As they say - a picture speaks more than a thousand words.... so I keep quiet now and let you decide for yourself if it is worth while investing in a book stand.
PS: Did you notice how she is working at sub-optimal lighting conditions, if yes, then you did really internalize lesson 6, hahaha.