CHROMEBOOK - HIGH CONTRAST MODE
Have you ever seen your child's (or your student's) Chromebook with the screen colors reversed? The normally white screen is black instead and the colors of things all seem wrong. This is because they have inadvertently (or intentionally) enabled High Contrast Mode.
Chromebooks come with a High Contrast Mode built in for the purpose of making it easier to read in low light conditions or for people with photosensitivity issues. It can be turned on or off in the Accessibility Menu, which is available through the Quick Settings Panel (Click near the time in the lower right of the screen).
Or you can simply use the keyboard shortcut of CTRL, SEARCH and H to turn it on and off. The SEARCH Key is the key with the magnifying glass on it, right below the TAB key on the left side of the Chromebook keyboard. Quick and easy to turn on and off, and understandable how sometimes a student can get stuck in that mode by hitting the wrong key.