Center of a-Tension

Source: G.K. Bloemsma

Type: Investigation

Theme: Physics

Grades: 5, 6, 7, 8, 9, 10, 11, 12

Learning Target: Students will measure the change in mass with various pulley systems and analyze classroom data.


800px Pulley3a.svg (Wikimedia)This project is designed for groups of three or four.

Objective: To develop an efficient pulley system out of common household items.

  1. Review the materials you have available. Materials may include:
    1. Lines: rope, cord, string, fishing line, rope
    2. Pulleys: bobbins, spools, rings
    3. Hardware: hooks, S-hooks, I-screws
    4. Short boards for upper support
    5. Weights (between 1 kg and 9 kg): water bottles, bricks, books 
  2. Plan your pulley project. You will need to design it so, you can take two different weight measurements, and at minimum four lines holding your rope (middle school students: minimum of 2 lines). Create an annotated sketch of your components. Digital ink is OK. Please list all of your materials and label them in your drawing.
  3. Research your pulley system. Is there a name for your configuration? When was it invented? In a minimum of three paragraphs, describe how your pulley system will be constructed and provide any historical context.
  4. Build your pulley system. 
  5. Record your data in a class spreadsheet (Sheets). Be sure to include the weight of the object before you attach it to the pulleys.


  1. Word document or PowerPoint.
    1. Title of your project and your name(s).
    2. Context paragraphs.
    3. Your annotated sketch.
    4. Your data (data must also be entered into the class spreadsheet). Minimum of three measurements, which includes the intial weight of the object. Analyze your data. Why did your measurements have an error?
    5. Photo of your final pulley system.
  2. Document your project development with a short video.
  3. Peer Review.



Exit Ticket
CCSS Math Practice
  • I can use appropriate tools strategically.
  • I can look for and express regularity in repeated reasoning.
NGSS Crosscutting Concepts
  • Scale, Proportion, and Quantity