Today we will work on iteration and design while building ziplines!

We will also consider how gravity and friction are forces that act on ziplines.

  1. Hang a zipline (heavy string) across your classroom – have it go from a high point in the room to a lower point. It needs to be at approximately a 45 degree angle. If it is too steep their contraptions will fall too quickly, and if it is not steep enough their zipline contraptions will not move.
  2. Collect materials for your students to build zipline contraptions:
    1. Materials can be just about anything from Legos to cardboard, but some good things to collect are paper, cardboard, pipe cleaners, plastic/paper cups, popsicle sticks, coffee filters, etc. Don’t forget the masking tape, scotch tape, and hot glue!
    2. You will also need some small ball – a ping pong ball works best, but a marble or golf ball would work as well
  1. Today we are working on iteration and design. Students will quickly build their first attempt at a contraption, but it will most likely not work the way they expect it to the first time. That is ok! Have them keep a written record of the times they tried, how long it took their zipline contraption to get down the zipline (Time it!) and an observation of what happened. As they do this they are trying different things to see if they can make it better.
  2. We should also be talking about gravity (the force that pulls things down towards the earth) and friction (the resistance that one surface or object encounters when moving over another). Can students pinpoint these different forces?

If I use a straw to drink out of a glass, why does the liquid stay on the bottom of the glass?

Using the materials that you are given, design a contraption that can travel down the string and carry the ball – YOUR PASSENGER!- safely to the bottom of the zipline!

Your zipline contraption must:

  1. be able to get on and off the zipline without breaking the zipline

  2. be able to release “your passenger” at the end of the journey down the zipline

  3. Keep your passenger alive throughout their journey!

  1. How long should your first design take you?

  2. How often should you or did you test?

  3. How much information did you write down after each test?

  4. What can you use to help center the weight of your contraption on the zipline? (should the weight be centered?)

  5. If your zipline contraption isn’t moving down the zipline, which materials should you try instead?

  6. Can you keep “Your passenger” inside of your contraption through padding it?

  7. Can you use friction to speed up or slow down your contraption?

  1. What are you most proud of about your contraption?

  2. What gave you the most trouble?

  3. Did you make changes a little at a time, or scrap the whole thing and start again? Would you do that again?

  4. Can gravity make your zipline contraption travel UP the string?