User reported issue: student who is color blind cannot differentiate atoms/molecules.

[oliver-phet]

I've used your simulations for years in my classroom and I've always been so pleased with them. I recently noticed you have an accessibility tab that links to all of the simulations with accessibility features. This year I teach a student who is color blind. The Balancing Chemical Equations simulation and game has always been a helpful tool but is difficult for this particular student to use because the atoms and molecules are color coded and not labeled with any other form of identification. To this student, all of the atoms look the same and he was struggling to count how many atoms of each element he had on each side of the equation in order to balance it. PhET has always been great about updating their simulations, so I am writing to request some form of color blind accessibility for this simulation as well as other simulations that depend heavily on color coding. Thank you for your attention to this matter and for keeping chemistry inclusive for all students!

Assigning to @arouinfar for now, though this may need input by the accessibility team.

[arouinfar]

@oliver-phet it would be helpful to get more specific feedback about which atoms are hard to differentiate. I played several different levels and compared the various colorblind preview options, and I'm not immediately seeing any issues. The levels are randomly generated, however, so it's certainly possible that there are some problematic combinations.

[oliver-phet]

Reply from teacher:

My student specifically has trouble differentiating between green and red colored atoms. He also has trouble differentiating atoms when they are only slightly different in color. For example, if a light red atom and a white atom are paired next to each other he can't see enough contrast to tell the difference between the two. The same would go for a light gray atom next to a white atom (see attached screenshot) or a light green and white atom. These were his main difficulties. If the atoms were widely different in size, he was able




to figure out which atoms were which most of the time. When I replayed all three rounds of the game, I noticed that chlorine (a green atom) only came up once in all three levels. If that green atom is paired with a white or red atom (as in the case of any chlorate (ClO3) molecules) he would really have a hard time. Thanks for your support!

Another example of colors he would have a hard time differentiating between would be purple and black. Not something that comes up in atomic models a lot, but something I heard him say that might be helpful!

[arouinfar]

My student specifically has trouble differentiating between green and red colored atoms.

I noticed that chlorine (a green atom) only came up once in all three levels. If that green atom is paired with a white or red atom (as in the case of any chlorate (ClO3) molecules) he would really have a hard time.

I reviewed the possible challenges and confirmed that chlorine (green) is never paired with oxygen (red).

For example, if a light red atom and a white atom are paired next to each other he can't see enough contrast to tell the difference between the two. The same would go for a light gray atom next to a white atom (see attached screenshot) or a light green and white atom.

None of the colorblind previews (pasted in below) show issues with white atoms and those of other colors. Additionally, the white atoms represent Hydrogen, which is always significantly smaller than the other atoms. So even if the colors are hard to distinguish, the size difference is significant. I'm not trying to invalidate this student's experience, but it's possible that there is some other issue.

I'm not sure what we can do about this, short of some sort of high contrast mode like we have in Build an Atom. I'll assign to @kathy-phet to prioritize.

[pixelzoom]

Deciding on better colors would probably be easier if they could be tweaked using the Color Editor. But making the atom and molecule colors dynamic would be a big lift -- unless you were OK with the colors not updating until the Game challenge changes. It would also require redoing the memory tests in #155, since making colors dynamic has a high probability of introducing memory leaks (due to listeners added to ProfileColorProperty instances).