Sid the Science Kid: Optical Illusions

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Sid can’t believe his eyes! At breakfast, his pancake looks smaller than Zeke’s, but they’re the same size! How can this be? It’s an optical illusion! Mom and Dad explain that sometimes your eyes and your brain play tricks on you and things aren’t always what they appear to be. But there’s something that causes Sid’s pancake to look smaller, like being on a larger plate than Zeke’s. Join Sid as he learns about different types of optical illusions, then see if you can find optical illusions around you.

Learning Concepts

Observation , Investigation

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Hey, you're a scientist, like me! Come discover with Sid the Science Kid.

"The pancakes are ready!"


"There's one for Zeke and one for you."

"Hey, why is this a smaller pancake?

I mean, look how much bigger Zeke's pancake is than my pancake."

"Nope, same size, Sid."

"I'll use my trusty ruler to check 'em, Dad."

"Okay Siddo, but I promise they're the same."

"Okay, so the bigger pancake measures five inches.

And over here, the small one measures . . . five inches!

Incredible! They're the same, but how? Aw! Dad, how can their size be the same?"

"Well, I'll tell you, Sid.

Your eyes were tricked by what's called an optical illusion.

Your brain told you that the pancake on the left was bigger, but actually the two pancakes are the exact same size."

"You mean, I can't believe my own eyes?!"

"Well, it's more like your brain played a trick on you."

"My brain played a trick on me?

Hold on. Something else must be different if the pancakes are the same size."

"You're on the right track."

"Well, the pancakes are the same size, but the plates are different. The plate on the left is smaller!

That's why I thought the pancake on the left was bigger than the other one.

Optical illusions are amazing!"

"Now take a look, Sid. I've got another one.

What animal do you see in this drawing?"

"Um . . . a duck!"

"Wait. A duck? It looks like a little rabbit to me."

"Huh? No, that's a duck."

"If you see a duck, you imagine that this is his bill, these are his eyes . . . and this is the back of his head."

"But watch this.

On the other side, we can see a mouth, an eye, and a long pair of ears. And that makes a rabbit appear!"

"Yeah, I see the rabbit! So I guess Dad and I were both right!"

"That's why it's an optical illusion. It's a picture that can show different things."


"At first, you see only one, but when you keep looking, you can see the other.

What animal do you see here?"

"Mm, a cat!"

"This time, I agree with Sid! That is definitely a cat!"

"Are you both sure? Because you're both wrong.

See, if I push in closer, I can change your cat . . . into a little white mouse!"

"Incredible! Hey, Mom, do you have any more optical illusions?"

"Yes, look at this straw sticking out of this glass of water."

"Yeah, that's funny, the straw looks crooked."

"Sid, I think you’re right. That straw looks crooked to my eyes too."

"But if you take the straw out, you can see that it's straight. The water causes the illusion."

"Wow, I know all about optical illusions now. I'm gonna go check on something. Thanks!"

"You're welcome."

Have you ever looked up in the sky at night and seen the man in the moon?

Oh, there he is now! I see a face with two eyes, a nose, and a big smiling mouth.

But now that I know all about optical illusions, I know there's no man in the moon.

Hey, scientists, you know what you can do is look for your own optical illusions! I'm sure you're surrounded by tons of 'em.

It's time for me to go to bed! So remember to keep on discovering!

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  • Written by: Michael Foulke
  • Produced by: Lisa Henson, Brian Henson, Halle Stanford, Bradley Zweig
  • Directed by: Greg Fera, Katy Garretson, Dean Gordon, David Gumpel, Brian Henson, Hugh Martin, Kirk Thatcher, Allan Trautman
  • Copy edited by: The Linguistic Edge


  • Sid: Drew Massey, Misty Rosas
  • Gabriela: Alice Dinnean, John Munro Cameron
  • May: Julianne Buescher, Dana Michael Woods
  • Gerald: Victor Yerrid, Alon Williams
  • Susie: Donna Kimball, Sonya Leslie
  • Dad: Victor Yerrid, John Munro Cameron
  • Mom: Alice Dinnean, Sonya Leslie
  • Grandma: Julianne Buescher, Dana Michael Woods
  • Zeke: Donna Kimball, Alon Williams
  • Dr. Cordova: Alice Dinnean, Kristen Charney, Michelan Sisti
  • Philbert: Victor Yerrid, Bruce Lanoil, Daisy

Sid the Science Kid

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