A random thought regarding this article and word association: A ‘pen’ can have two modes, and a built in Bluetooth transmitter for communication to and from your smartphone.
The initial mode of the thin ‘pen’ like device allows the person/student to read the question using Optical Character Recognition by moving the thin pen like device over the question. The question is wirelessly transmitted to your smartphone, then the second mode of the device receives the answer from the smartphone in your pocket using the smartphone search, and can allow the user to have a simple output of ink, by rolling the highlighter against a white background. The inverse of the highlighted area would contain the letters for the answer. A bonus is to have disappearing highlighting ink. Just an idea, kids.