At home, screens were cathode ray tubes in which a spray of electrons, steered by magnetic fields and attenuated by a shadow mask, struck red, green, and blue phosphors. The high-pitched noise given off by the electronics of a CRT TV monitor create physical pain in modern-day students. TV watchers of a certain age somehow tuned that 10 kHz+ whine out.
Today, screens are everywhere, and virtually all are based on light-emitting diodes. But the RGB nature of color imaging remain. That's what this activity is about.
Color mixing and pixel geometry. Surprising enough and instructional enough to be worthwhile.
Pixel Peeping Student Document (Google Docs copy link)
(media links are included in the student document)
The PhyzSommelier says this activity pairs nicely with
PhyzLab Springboard - Fun With Colors (Google Docs copy link)
Conceptual Physics Alive: Light & Color (TpT Link).