Green Eggs and Sam

Sam took out his favorite watercolor paints and announced, "I'm confused."

He pointed, "Red, blue, yellow-three primary colors. You can't make them by mixing other colors. But you can use them to make new colors. That's what you always said." Sam dipped his paintbrush in the water. "Red and blue mix to make purple. Blue and yellow mix to make green. Yellow and red mix to make orange. And if I mix red and blue and yellow all together, I get yucky blackish."

Mom sat down across from Sam. "Nothing confusing so far, Sam. You've painted a bunch of purple grapes with green leaves in a big orange bowl on a yucky blackish table. Those grapes look good enough to eat! What's the problem?"

Sam scowled. "The problem is that when I was helping Ms. Jeffers do the lights for our school play, she said the primary colors are red, blue, and GREEN. When she mixed red lights and green lights she got a YELLOW spotlight. And when she mixed the red and blue and green lights together on the stage, it made everything bright WHITE." Sam crumpled his painty paper. "And that's confusing!"

"Ahhhh," said Mom. ''I see your point." She tapped her finger on the table. "Before we talk about primary colors, we need to talk about light. Did you know that white light isn't really white? It's a mixture of all the colors of the rainbow-red, orange, yellow, green, blue, and violet. Here-grab a clean sheet of paper, and I'll show you."

Sam followed Mom as she took a crystal wineglass from the china cabinet and went our on the deck. "OK, Sam. Put the paper down, and hold the glass out over it so the sunlight shines through the glass onto the paper. Now turn the glass a little-try the other waythere! see the rainbow on the paper?"

Sam twisted the glass back and forth, and sure enough, a little rainbow showed up on the white paper.

"That rainbow is caused by light bending as its goes through the crystal. Each color in the white light bends a slightly different amount in the crystal, so when the light leaves the crystal the colors are separated. The crystal splits the light from the sun into the colors of the rainbow-but the colors were part of the light all along."

Mom put the paper and the glass away , and had another idea. "Turn on the hose, Sam," she said. She fiddled with the nozzle until a fine spray came out. "Now stand with your back to the sun, and point the hose up in the air. see the rainbow in the spray?"

Sam did. "Cool!" he said. He sprayed the hose up and down, back and forth, while the rainbow danced in the shower.

"This time the rainbow is caused by sunlight bending as it passes through the drops of water," said Mom. "Just like the crystal, the drops separate the white sunlight into a band of colors."

Mom and Sam went back inside. "When Ms. Jeffers shone her red and blue and green lights on the stage, she was doing the opposite of what we just did," Mom explained. "We split the white sunlight into different colors. Ms. Jeffers put those different colors back together to make white."

Mom tousled Sam's hair. "Are you still with me? When you're working with light beams, the primary colors are red, green, and blue. That's why Ms. Jeffers could mix red and green lights to make yellow. And it's why she could mix all the colored lights together to make white light."

"So when you're mixing paint," said Sam, "the primary colors are red, blue, and yellow. But when you're mixing light, they're red, blue, and green."

"Right," said Mom. "And just like with paint, you can mix the three primary colors of light to make millions of new colors. That's how all the colors are produced on a computer or TV screen."

Sam doodled with his paints. "Ms. Jeffers's green light is a primary color. But my green paint is blue and yellow mixed together." He thought a minute. "What about my green marker? What kind of green is that?"

Mom grinned. "Oooooh-I was hoping you'd ask! I have such a good way to answer you!"

Mom took a paper coffee filter from the cupboard and some scissors and the stapler. "You get a juice glass, Sam, and a pencil. And your green marker!"

Mom cut a narrow strip from the coffee filter. She folded one end over, then stapled it to make a loop. "OK, Sam," she instructed. "Make a green dot here, near the bottom of the strip. Now poke the pencil through the loop, and hang the pencil over the glass, so the strip dangles down in it."

Mom carefully poured some water into the glass, until it just barely touched the bottom of the paper but didn't reach the green dot. "Now we watch," she said.

"What are we watching for?" Sam asked.

"Wait and see," Mom said, looking mysterious.

So Sam waited. First just the bottom of the filter strip was wet. Then the water started creeping up the paper, until it reached the dot of green marker.

"It's spreading out!" Sam said. "My green dot's all smeary! It's not green anymore!"

Sure enough, the little green dot was turning into a watery, washy smear of color-blue at the top, yellow at the bottom. There was still some green showing, but mostly it was yellow and blue.

"Ha!" said Sam triumphantly. "You're not really green! You're blue and yellow! Wait till I tell Ms. Jeffers!"

Then Sam had an idea. "Hey, Mom," he said. "What happens if we mix blue food coloring with yellow eggs? Will we get green scrambled eggs?"

'Only one way to find out," Mom said happily. "Get the food coloring, Green Eggs and Sam!"

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