From the brains behind brains on, this is the Moment of Um.

Moment of Um comes to you from APM Studios.

I'm Squagellum Trunk, Wizard in Training.

Um.

Okay, this time it's going to work.

Presto!

Ugh, toadstools.

Not again.

It takes a lot of studying and hard work to become a wizard.

This year, I'm supposed to be learning transmutation

spells. That's when you turn one thing into another thing, like turning a leaf into a playing

card, or a handkerchief into a hamster, or a desk into a donkey. I've been trying for weeks to get this spoon to turn into a fork,

and all I've managed is a lopsided spatula. But I'm going to keep trying. I mean, there are

tons of things that can turn into other things in nature, like caterpillars that turn into

butterflies, or acorns that grow into oak trees,

or even gloopy wet concrete that turns into tall, hard walls.

I don't actually know how that last one works.

I'll have to look through my spellbooks.

I really want to figure this out because Camden wants to know, too.

My name is Camden. I'm from New Mexico.

My question is, how does concrete get hardened? So cement and concrete are two different things. I am

Matthew Adams. I'm an assistant professor at New Jersey Institute of Technology. Cement is the fine gray

...