You may have spotted one of these "fidget toys" these here interwebs or IRL recently.

Proponents of fidget widgets — which are aimed at people of all ages — say that having something to fidget with reduces anxiety, improves memory, and helps people concentrate, and claim that the toys can be especially helpful for kids who are on the autism spectrum or have ADHD.
As a result, they've become super popular with students...and a lot of teachers are not here for it.

Several schools have actually banned the toys outright.
