He recently taught us what a mole is. I used to think a mole was just an animal like me, but I learned it’s also a way chemists measure things that are so small we can’t even see. A mole of something ...

Voles and moles are very similar animals, and both creatures are kind of a nuisance. Despite their diminutive statures, they make their presence well-known by wreaking havoc on gardens and lawns.

As in some insect species, the queen is the only naked mole rat female to breed and bear young. Worker animals dig the burrows that the whole clan inhabits, using their prominent teeth and snouts.

The word "mole" suggests a small, furry burrowing animal to many. But in this TED-Ed lesson, we look at the concept of the mole in chemistry.