Hi, I'm Deysi from Design Squad, and I'm here with Anna, Ethan, and Arun.

ANNA: Our mission is to make a robotic arm using cardboard, string, and straws.

DAISY: NASA uses robotic arms because lots of its missions don't involve people.

Also, mechanical arms are much stronger than human arms.

Our robotic arm needs something flexible, something that can be pulled without breaking, like string.

ANNA: That works.

DAISY: String is good in tension.

It also needs something rigid for the bones, like cardboard, which is good in compression.

ARUN: Our robotic arms are a lot like human arms.

They have a hand, a forearm, and an upper arm.

(faint whistling) ARUN: But people don't need a string to move their fingers because they have arm muscles to pull their tendons.

ANN: Sometimes things don't go the way you want them to.

(laughter) ARUN: So if you pull this string, it moves this way.

DAISY: That's awesome.

You know, the cool thing about robotic arms is that it's a system of levers.

So when you pull, the sections move around the pivots, making the end of the arm move a lot.

A baseball bat is also a lever.

You put lots of force in one end, and you get lots of movement in the other.

I'm trying to make it so if you pull this, it moves backwards.

But it doesn't.

ANNA: The string keeps getting bunched up.

Maybe we could use fishing line, it's more slippery.

DAISY: Have you tried picking something up with it?

I need to find something to hook it around.

Okay.

Yeah.

(laughing) I got it!

Let's see if these robotic arms could pick up some space rocks.

Higher.

Yes, we got it!

Yes!

DAISY: For the directions on how to make this, and to see lots more activities related to NASA's missions, visit the Design Squad website.

(laughter)