Build a Crane

Brief description: Students will use LEGO and craft materials to construct a crane. This activity fits particularly well in a simple machines unit plan, as it combines many simple machines.

Grades: 3, 4, 5, 6, 7, 8

Time: 2 hours

Keywords: crane, simple machines, pulley, lever, wheel and axle

Lesson Objectives:

  • Students will understand the parts of a crane and how cranes can be used
  • Students will be able to identify the simple machines in a crane


  • LEGO
  • String
  • Cardboard
  • Popsicle Sticks
  • Cups
  • Straws


  1. What is a crane?

    1. A crane is a type of machine that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy things and transporting them to other places
    2. This video can show students a crane in action.
  2. If doing this in a simple machines unit, have students identify simple machines they see in the crane. More information can be found here.
    1. Pulley– the cable uses a pulley system to move the load vertically.
    2. Lever– the arm of the crane is the lever.
    3. Wheel and Axle– 1) The trolley 2)if a smaller moving crane, the wheels and axles are used to drive the crane around.
  3. Identify parts of a crane.

    1. What parts of the crane?
    2. How do these parts move? Horizontally? Vertically? Where is the load carried?
    3. Where does the cable connect? Which simple machine involves the cable?
  4. Allow students to build their cranes out of the materials provided. Example projects:
  5. Have students test their designs by lifting a water bottle (or other weighted object). Common problems that arise during testing:
    1. Counter weighting. Their designs often tip over due to the weight of the test object.
    2. Cranks. Encourage students to build pulley systems and cable cranks so they can release and draw in their cables without just pulling string and giving slack.
    3. ??
  6. Wrap Up. Discuss what worked well and what did not work well. What materials were easier to work with than others? What was the hardest part of this challenge? If doing presentations, do a “glow” and a “grow” for designs.

Example Projects from Students:

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