A Winch Lightens the Load (Student Instruction)

Haul water—or buckets of stuff—up and down by making a well winch.


Bridge Design Engineer Katie Kelly introduces the Marble Run challenge



  • stuff to make the posts or struts for the winch: cardboard tubes or boxes; packing blocks that can be cut, like molded pulp or Styrofoam
  • cutting board or rectangle of cardboard for the base if you can’t tape directly to a hard surface
  • empty spool from ribbon or thread for the drum
  • straws, pencils, pens, or skewers for the crank
  • string or thin ribbon for hauling the bucket up and down
  • tape
  • scissors
  • paper cup for a bucket
  • light stuff to put in the cup, such as candies, paper clips, beads, cotton balls
  • ledge, such as the edge of a desk, table, or counter
  • sketching materials


How do people haul buckets of water up out of a deep well? For centuries they’ve used a simple machine called a winch.

We challenge you to design a well winch that can lower an empty bucket down into a “well” at least one foot and lift the full bucket up again—without spilling any of it.

There are 3 constraints for this challenge (an engineering constraint is a limitation on your design):

  • Use only the materials provided, but you don’t have to use all of them.
  • The drum of the winch rotates to release the string or wind it back up.
  • The winch is operated by a handle, called a crank.

Brainstorm Designs

What do you know about wells? Maybe you’ve seen pictures of them in storybooks. Engineers get ideas from any and all sources! Draw a well from memory or consult a picture. Label the:

  • posts, which hold the winch up off the surface
  • drum, which the string will wind around
  • crank, which you’ll use to turn the drum
  • rope that will attach to the bucket

Choose a ledge from which to lower or raise your bucket. Desks, tables, and counters are good options. If you can’t tape directly on the surface, use a piece of cardboard that lines up with the edge of the surface instead.

Build and Test

Make your winch. The string needs to attach to the drum so that it winds around and then unwinds without tangling. Think about how to attach the bucket to the string so it doesn’t tip the contents out.

When it’s time to test, make sure the base of the winch will not move, if you haven’t taped the winch directly to the ledge.

To test your winch, lower the bucket. Fill it to the brim with the stuff you’ve collected. Raise the bucket as high as it can go.

Evaluate and Redesign

How well did the winch work? What problems did you encounter? Maybe the drum didn’t turn smoothly or the crank fell off. Engineers rarely get it right on the first try and they learn a lot from their mistakes.

Make Change and Try Again!

Make improvements and try your winch out again.

Or, make a different version. Build a winch that lowers a bucket into a bowl of water and brings the full bucket up again, the way a real well winch does. What if you made a bigger winch that hangs from part of the playground? How heavy a load could it hold?

Share Your Results with a Teacher, Parent/Guardian, or DiscoverE!


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