It usually is. You can usually find some research or news about same tech used.
from 2013 article [1], though it seems not practical [2]:
"W2Plastics has shown the viability of magnetic density separation, where flakes of shredded plastic such as polyethylene or polypropylene are mixed into a magnetic fluid made by adding iron oxide to water."
I am not sure which one is better to show kids they discovered something existing, or praise them like this