How can you move something great distances with something as simple as a string? In this experiment, you’ll use a Ziploc® brand sandwich bag, string, and two chairs to build a mini-gondola. Once you construct your system, fill the bag with a secret message and pull the string to deliver your message! How does pulling and pushing the string change the direction of the system?

  1. Ages: 3 - 9

  2. <30 minutes

  3. A little messy

  4. Grownup needed

Step-by-step tutorial

  • Step 1

    Gather your materials.

    Photo reference of how to complete step 1

  • Step 2

    Set up your gondola stations. Align two chairs back to back, about three feet apart from each other.

    Photo reference of how to complete step 2

  • Step 3

    Cut a piece of string long enough to loop around the top of the chair legs.

    Photo reference of how to complete step 3

  • Step 4

    Tie the ends of the string together and make sure it’s taut. (No sagging here!) Use two small clothespins to clip the Ziploc® brand sandwich bag to the string.

    Photo reference of how to complete step 4

  • Step 5

    Have your friend stationed at one chair and position yourself at the other chair. Write a secret note and place it in the bag to send to the other side. Pull the string toward yourself to send the bag (and your note) toward the other chair until the bag reaches your friend. Your friend can swap out the note and send something back. What other kinds of things can you send along?

    Photo reference of how to complete step 5

  • Learn moreMagnifying graphic

    Pull the string in different directions to move things along. If you tug on the string on the side with the gondola attached, it'll move toward you. If you pull on the other side of the string, it'll move in the opposite direction, away from you. This happens because the string wraps around the chair and connects, creating a cable car system. How else can you pull (or push) on the string to make the gondola move? If you pull faster or slower how does that change the gondola's speed?

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