READER'S THEATER

Characters: Shani, Luisa, and Journey

Setting: Shani, Journey, and Luisa are at the beach trying to watch their friend Kenzo surf.

Shani: Can you see him?

Journey: Who? Kenzo? No, not really. I think he’s out there in that pack of other surfers. Looks like they’re all just sitting on their boards, waiting to catch a wave.

Luisa: You guys know there’s this whole thing about whose turn it is right? It’s called the “line up.” There’s a place on the wave where it’s the best spot to try to catch the wave. The surfers all stay off to the side and wait their turn to catch a wave. It’s a little more complicated than that, but that’s the general idea.

Shani: There he is! I see Kenzo! Oh wait, now I don’t anymore. (pause) There he is again! He’s kinda just going up and down. All the surfers are–just sort of bobbing up and down. Kenzo’s got the green board shorts on. Do you guys see him?

Journey: I see him now. It looks like he’s just sitting on his board, but it's getting close to his turn. It's gotta be soon now...

Luisa: It depends on the frequency of the waves.

Journey: You mean like how often they’re coming?

Luisa: Yea, pretty much. Some days it might be high frequency–just one wave right after the other. Other days, you might be waiting longer between waves. That would be lower frequency, and on those days surfers get real chippy about whose turn it is ‘cause there aren’t as many good waves to catch.

Shani: Why is Kenzo just bobbing up and down? Why don’t the waves push him towards us on the shore? He’s just going up and down. Look there he is again!

Journey: I’m sure Luisa knows. She seems to know a lot about waves! (eye roll)

Luisa: So those surfers are just bobbing up and down because of the wave's amplitude. You can think of that as how far they rise up with the crest of the waves or how far they drop down in the trough of the waves. Oh, and how far it is from one crest to the next, or from one trough to the next, is called the wavelength.

Shani: OK I think I get that, but then why does my dad say I'm on my own wavelength?

Journey: Um... because your dad knows you very well?

Luisa: (refocusing conversation) Anyway... the energy of these waves we're watching moves through the medium, water.

Journey: Medium water? It looks like extra large water to me.

Luisa: Not that kind of medium! I mean something energy can move through... like air, or land, or a wire... lots of different stuff. But here the medium is water.

Shani: It sort of looks like the waves are bringing in water from way out in the ocean...

Luisa: ...but that's not true! Really the water here near the shore is just going up and down, and maybe a little back and forth.

Journey: So when I see a water wave, I’m really just seeing energy traveling? And the water isn't going anywhere?

Luisa: It's moving a little, but hardly at all compared to the wave energy.

Journey: That is too strange. Now my brain hurts...turn up that radio. Let’s just chill.

Luisa: You know those are waves, too, right?

Journey: I said CHILL Luisa!

Shani: Don't be rude Journey. So Luisa, you mean like sound waves? Or radio waves?

Luisa: Both! The radio receives radio waves that were transmitted from the radio station. Those are electromagnetic waves. They can even travel through space. They don’t even need a medium to travel through. Devices we use all the time like radios actually change the electromagnetic radio waves into sound waves.

Journey: Electromagnetic? That sounds dangerous.

Luisa: Now it's YOUR turn to chill, Journey. Electromagnetic waves are everywhere.

Journey: Everywhere? I don't see anything...

Luisa: Um... You don't see anything? Journey, the only reason you can see ANYTHING is because of light waves!

Journey: Oh. I guess I can't think because of that noise from the ocean...

Shani: And that noise would be...

Journey: What? I can't hear you because of the wind.

Shani: Oh come on, Journey! Sound waves!

Journey: I knew that! Really! I know all about sound waves. They are basically little compressions in a pattern that travel out and then get picked up by our ears.

Luisa: You got it, Journey.

Journey: I’m definitely learning more today than I normally do. I think I like it. But wait, can’t sound travel through water too? Dolphins transmit sounds to each other, right? (Journey’s cell phone rings) Hang on, let me get this call.

Luisa: You know that cell phone uses radio waves, too, right?

Shani: Really?! I sure do love those radio waves.

 

DISCUSSION

Shani says, "There he is! I see Kenzo! Oh wait, now I don’t anymore. (pause) There he is again! He’s kinda just going up and down. All the surfers are–just sort of bobbing up and down."

How would you explain why the surfers are in and out of view from the beach? Use a sketch if it helps you explain.

During the "line-up", Kenzo and the other surfers were waiting their turns in the water just bobbing up and down with their boards.

Why weren't the surfers getting pushed toward the shore by the waves? Why did Kenzo go in and out of the view of his friends watching from the shore?

Luisa says, "Now it's YOUR turn to chill, Journey. Electromagnetic waves are everywhere." And Journey responds, "Everywhere? I don't see anything... or hear anything either..."

Do you think waves are always visible and hearable? Why or why not? Use evidence from the Reader's Theater to support your thinking.

When you hear a sound, what you actually hear is a vibration, or sound wave, which travels through the air to your ear. Whether the sound is coming from a voice, a speaker, or an instrument, something has to vibrate and compress the air molecules around it. The compression of those air molecules creates a wave: molecules bump into each other all the way from the sound-maker to your ear!

Based on the description above of how sound waves work, why did it get harder for Journey to hear the others' voices when it got windy?