Quick update: On finishing functions and colorblindness

I am about to finish my review on basic functions. Since I finished the calcFTWfree chapter I wanted to check out other resources on function to make sure I did not miss anything. In iBooks store I found this, for a lack of a better word, book:
School Yourself Hands on Pre-Calculus
I hesitate to call it a book because it is so much more. For example, it has interactive exercises and even video explanations within the pages you are reading.
 
In the functions section you can play around with functions and even make your own by dragging your finger along an x,y plane. It's seriously cool and I would have loved to have something like that back in school. To make it even better, it's free. If you know any kid who is struggling through pre-calculus because he or she cannot wrap their heads around the concepts, let them know about this book. They will need access to an ipad or ipad mini.
 

Getting back on track, In the middle of one of the hands-on exercises on positive or negative functions (part of functions whose outputs are in the positive or negative side of the y axis), the exercise looks like the picture opposite.
 
Everything was great until I realized the chart was supposed to have two colors, one for the segment over the x axis and another for the segment under it.
 
The problem is I could only see one color, because I am colorblind.
 
Colorblindness is a condition that affects between 1% to 10% of males and less than .05% of women depending on what studies you look at. It is not vision loss, so it is usually labeled as a chromatic deficiency. For a medical explanation on colorblindness you can go here.

My colorblindness is usually, at most, a nuisance. I have learned to live with it. I know what color clothes to buy so they would match. I have taught myself to recognize colors by association and references. And most of the time I can live a very normal life with it. My condition does have its drawbacks. I need as second set of eyes when I am cooking, or eating, meat at any term bellow well done. I would also have trouble describing a car's color after a hit and run, as I experienced once. If you would like to know what it feels like to be colorblind from someone who can explain it better than I ever could, see this 9 minute documentary called There is no such thing as color. If you want the short and sweet version checkout the 3 1/2 minute video at the bottom of that page, it's made for kids but I found it very enlightening.
 

 

Getting back to my problem with the chart, I decided to write the people of SchoolYourself with a suggestion of making the color changes more distinct, or even better, to use a dashed line to differentiate both segments to help colorblind people "see" them better. To my amazement they answered the same day, thank me for the comment, and told me they will make recommendations for future editions. That was a great response time...did I mention their book is free? And just in case, I am in no way affiliated to SchoolYourself other than as a consumer of their book.

 

Let me know in a comment about other ways I can review my functions.

 

Update: The engineers in charge of SchoolYourself wrote me again with a picture that incorporated my suggestions into their charts to make them easier to see by people with Colorblindness. They asked for my feedback. I was sincerely touched by this effort. They now have a fan for life.