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Overview: Water on a StringNarrator: Whether it's your first time or you're an old pro, leading a group of kids through an activity requires the same basic steps:
- Prepare
- Introduce the Activity
- Try It Out
- ZOOMon
- and Share Results
We'll use Water on a String as a sample activity to explain these steps. Get to know Water on a String by watching the ZOOM cast in this next clip.
VIDEO CLIP
Summary: Working in pairs, ZOOM cast members use two cups and a two-foot piece of string to see if they can transfer water from one cup to the other using only the string. The cups must remain two feet apart.
(Description: Shing Ying holds two six-ounce plastic cups. One is full of water and the other is empty.)
Shing Ying: Do you think we could pour the water from this cup into this cup? We could if you could just go like this (Description: She pours water from one cup to the other). But what if the cups always have to be two feet apart?
Mike: The only material we can use besides ourselves and the cups is string. Whichever team--either Kortney and me or Shing Ying and Estuardo--is the first to get the water from this cup (Description: He points to the full cup of water)...to the line of this cup (Description: Mike's finger traces a measuring tape to an empty cup two feet away from the full cup. The empty cup has a green line one third of the way up from the bottom)...is the winner. Ready, guys?
Shing Ying: Yep.
(Description: Each team has its own table with all of the materials on a tray.)
Team 1
Mike: All right.
Kortney: So...
Mike: All right. How could we do this?
Kortney: We could use, like...
Mike: We have to pour the water.
Team 2
Shing Ying: But if we somehow, like...cut a hole at the top (Description: She gestures to the full cup), and we knotted this (Description: She gestures to one end of the two-foot-long string and the full cup), and we knotted it to that (Description: She gestures to the other end of the string and the empty cup), and we lifted this (Description: She lifts the full cup in the air), and it was exactly two feet above, and we just poured it.
Team 1
Mike: Adhesion is the ability of molecules to stick together.
Kortney: Yeah. So...
Mike: So...How could we get the water to stick to this? (Description: He gestures to the string.)
Kortney: Well, since molecules want to stick together, maybe we should soak it and then try what we were thinking of before.
(Description: Mike dips the string into the full cup of water.)
Team 2
Shing Ying: So, if we tie this here...(Description: Shing Ying and Estuardo tie one end of the string to the rim of the full cup). Oh, we still have to make sure that the string is two feet long.
Team 1
(Description: Mike holds the full cup in the air with one end of the string pressed to the rim.)
Mike: Will that stick? (Description: Mike slowly pours water onto the string, catching excess water in an extra cup positioned on the table below the full cup. Water pours into the extra cup only, not down the string.) No, it's not...
Kortney: Doesn't look like it's sliding, either.
Mike: I would think it would just drain right into it. (Description: Mike pours again. A few water drops run down the string.) Oop!
Kortney: Ooh!
(Description: The water drops pause midway along the string.)
Mike: A little...
Kortney: A little higher.
(Description: Mike lifts his end of the string higher.)
Mike: Drops, go.
Team 2
(Description: Shing Ying and Estuardo's cups are now tied to opposite ends of the string. Shing Ying holds the full cup high in the air and Estuardo holds the empty cup on the table.)
Shing Ying: (Description: She gestures to Estuardo's cup.) If we put this cup down, like all the way down so this whole thing is straight (Description: Estuardo moves his cup down below the table to keep the string taut), and we did the exact same thing, it probably works. So, let's see. (Description: Shing Ying pours water onto the string, catching excess water with a rag. Water pours onto the rag only, not down the string.)
Estuardo: No.
Team 1
(Description: Mike continues to hold up the full cup with one end of the string pressed to the rim, and Kortney holds the other end of the string in the empty cup, which is down low.)
Mike: Tilt the cup.
Kortney: So it's like that? (Description: She tilts her cup toward Mike.)
Mike: Yeah.
Kortney: All right. Ooh, you've got some coming. (Description: Water drops start moving along the string and into Kortney's cup.) Ooh, I feel it. I can feel it.
Team 2
(Description: Estuardo now holds the full cup in the air and Shing Ying holds the empty cup. Estuardo pours water onto the string tied between the cups.)
Shing Ying:: Keep on pouring. That's a good speed.
Estuardo: Yay.
Shing Ying: (gasps) It's working. (Description: Water streams down the string.) We're almost there.
Estuardo: We're done?
Shing Ying: Yeah, I think we're done.
Team 1
(Description: Mike holds up the empty cup, which is now filled with water to the green line.)
Mike: Wow, I think we got it.
Estuardo: Here's the science scoop on why this works. Water molecules have a strong attraction to other water molecules. This means that they stick together really well. This is called "cohesion."
Kortney: Water can also stick to other materials, like string. This is called "adhesion." That is why when we poured the water down the string, it stuck to the water molecules on the string and the string.
Narrator: Now that you've seen Water on a String, think about how you'd use all five steps when you're leading this activity or any other activity. We've provided suggestions for each step of the process.
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