When we explain something to someone (or something) else, we often gain a better understanding of it ourselves.

There’s a lot to learn here. You know, for when you need to make a robot duck. Naturally, this is not the first time that anyone’s strapped a remote-controlled submarine on a duck decoy.

For example, US-based Sproutel has developed a robo-duck that lets children undergoing cancer treatment tap a "feeling card" representing a certain emotion against the duck's chest. The duck ...