Objective

By the end of this lesson, students will understand the concept of simple machines, specifically pulleys and trebuchets. They will investigate how the number of pulleys affects the effort needed to lift a load and how the weight and design of projectiles impact the efficiency of a trebuchet. Students will record their findings and apply scientific thinking to improve their designs.

Materials and Prep

• Different types of pulleys (single, double, triple)
• Weights for testing (e.g., small bags of sand or weights)
• String or rope
• Materials for building a simple trebuchet (e.g., wooden sticks, rubber bands, plastic cups)
• Measuring tape
• Notebook and pencil for recording results
• Stopwatch for timing launches
• Markers to label stations

Activities

• Station 1: Single vs. Multiple Pulleys

  Students will set up a single pulley and a double pulley system to lift the same weight. They will measure the effort required for each system and calculate the mechanical advantage.

• Station 2: Trebuchet Launch

  Students will construct a simple trebuchet and launch projectiles of various weights. They will measure how far each projectile travels and analyze how weight impacts distance.

• Station 3: Pulley Variations

  In this station, students will experiment with a triple pulley system. They will record how much easier it is to lift the weight compared to the single and double pulley systems.

• Station 4: Trebuchet Design Challenge

  Students will redesign their trebuchet to improve its efficiency. They will test different projectile shapes and materials, recording which designs launch the farthest.

Talking Points

• "What do you think happens to the effort needed to lift a weight when we add more pulleys?"
• "Can you explain what mechanical advantage means in your own words?"
• "How do you think the weight of a projectile affects how far it can be launched?"
• "Why is it important to record your results? What can we learn from them?"
• "How could we improve our trebuchet design to make it launch further?"
• "What do you notice about the efficiency of different simple machines? Can you compare them?"
• "How does using a pulley system change the way we think about lifting heavy objects?"