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Session 15: Compound Machines ⚙️

Overview

Grades: 3-4 | Duration: 40 minutes | Session: 15 of 17

Students explore compound machines, discovering how combining simple machines creates complex and powerful tools.

Session 15: Compound Machines

Learning Objectives

By the end of this session, students will:

  • Review the six simple machines

  • Understand how simple machines combine

  • Identify compound machines in everyday life

  • Design a compound machine concept

Session 15: Compound Machines

Materials Needed

  • 📸 Pictures of compound machines

  • 📦 Building materials

  • 🔍 Real compound machines (scissors, can opener)

  • 📓 Engineering journals

  • 📋 Simple machine reference cards

Catholic Integration

Saint Connection

St. Joseph the Worker — Patron of workers! His carpentry required compound machines like planes and drills.

Scripture

"Whatever your hand finds to do, do it with all your might." — Ecclesiastes 9:10

Opening Prayer

Dear God, thank you for tools that help us work. Like St. Joseph who worked with skill and dedication, help us appreciate the engineering of compound machines. Amen.

Lesson Procedure

Opening Circle (6 minutes)

  1. Simple Machine Review:
  2. Lever, Inclined Plane, Wedge, Screw, Wheel & Axle, Pulley
  3. Each makes work easier in one way
  4. Compound Machines:
  5. "What if we combine them?"
  6. Two or more simple machines working together
  7. More power, more possibilities!
  8. Examples:
  9. Scissors = 2 levers + 2 wedges
  10. Bicycle = wheels, levers, pulleys
  11. Wheelbarrow = lever + wheel
  12. St. Joseph — Used compound tools in his workshop

Main Activity: Compound Machine Discovery (26 minutes)

Part 1: Machine Analysis (10 minutes)

Examine Real Compound Machines:

  • Scissors
  • Find the levers (handles)
  • Find the wedges (blades)

  • How do they work together?

  • Can Opener

  • Wheel & axle (turning knob)
  • Wedge (cutting wheel)

  • Lever (handles)

  • Pencil Sharpener

  • Wheel & axle (handle)
  • Wedge (blades)

  • Screw (holds blade)

  • Other examples to find:

  • Stapler
  • Hole punch
  • Bike (if available)
  • Door knob

Record:

  • Name of machine

  • Simple machines inside

  • How they work together

Part 2: Design Challenge (12 minutes)

Challenge: Design a NEW compound machine!

Requirements:

  • Combines at least 2 simple machines

  • Serves a useful purpose

  • Sketch with labels

  • Explain how it works

Ideas:

  • Helper for someone with a need

  • Tool for a specific job

  • Improvement on existing machine

  • Solve a classroom problem

Process: 1. Identify problem/need (2 min) 2. Brainstorm solutions (2 min) 3. Design compound machine (6 min) 4. Label simple machines used (2 min)

Part 3: Design Share (4 minutes)

  • Share designs with class

  • Explain: What simple machines? What does it do?

Engineering Journal (5 minutes)

  1. List the 6 simple machines
  2. Draw a compound machine you examined (label parts)
  3. Draw your design (label simple machines)
  4. Write: "Compound machines are powerful because..."

Closing Circle (3 minutes)

  1. Machine Appreciation — "Look at compound machines around you now!"
  2. St. Joseph Connection — "Workers need good tools!"
  3. Closing Prayer — "God, thank you for the creativity to combine simple things into powerful tools. Help us work with skill and purpose. Amen."

Assessment

Observation Checklist:

  • Identified simple machines in compound machines

  • Analyzed real compound machines

  • Designed original compound machine

  • Explained how parts work together

Differentiation

For Students Who Need Support

  • Focus on scissors analysis

  • Partner design work

  • Design template provided

For Advanced Students

  • Build working prototype

  • Calculate mechanical advantage

  • Research complex machines

Wonder at Home 🏠

Family Activity: Compound machine hunt at home! Find 10 compound machines and identify the simple machines inside each. Kitchen tools, garage tools, toys—they're everywhere! Try designing one together!

Teacher Notes

  • Bring real tools for examination

  • Safety with sharp objects (scissors, can opener)

  • Great for St. Joseph the Worker feast day (May 1)

  • Consider Rube Goldberg machine extension

Previous: Session 14 — Ozobot Challenge
Next: Session 16 — Makey Makey