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  • Our STEM projects are designed so that participants get it wrong before they get it right. You will observe your students struggling as they attempt to create their own STEM projects. This process is an empowering experience, building perseverance, frustration tolerance and growing overall confidence! With your support, students will step out of their comfort zones to think, build and problem-solve for themselves.
  • Productive Struggle Moments
    - Peeling double-sided tape tests fingernail patience. Suggest folding a corner first, then step back.
    - Tying the knot to the cup (see Knot Tying Guide) may take three tries. Three tries is the point.
    - The over-under-over route is easy to get backwards, and a wrong route often still works, just differently. That is not an error to fix. It is data for the investigation below.

Time: 30 to 40 minutes (build plus experimentation)

Big idea: Simple machines change the size or direction of a force to make work easier. Students build a pulley wall, then reroute the string to discover what a pulley actually does.

Standards Snapshot: Virginia SOL + NGSS

Pick your grade band. The build is the same, the thinking changes.

GradeVirginia SOLNGSSStudents walk away able to…
KK.2: pushes and pulls affect the motion of objectsK-PS2-1 · K-PS2-2Show that pulling the string down makes the cup go up, and compare gentle and strong pulls.
11.2: forces change the speed and direction an object moves—Describe the cup’s motion and name the pull that causes it.
33.2: simple machines increase or change the direction of force; friction opposes motion (primary fit)3-PS2-1 · 3-5-ETS1-2, ETS1-3Explain that the pulley changes the direction of their force, and test which string route works best.
55.2: direct and indirect forces affect the motion of objects; energy and motion—Explain why a heavier cup is harder to lift, using friction and force in the explanation.
K–5X.1: Scientific and Engineering PracticesETS1 (Engineering Design)Predict, test a design, compare routes, and improve the build based on results.

Practices exercised (both frameworks): asking questions and predicting · planning and carrying out investigations · comparing designs and interpreting results · constructing explanations from evidence. NGSS Crosscutting Concept: Cause and Effect · Structure and Function.

Curiosity & Wonder

Do not define simple machines yet. Wonder out loud with your students:

“Construction workers lift steel beams way up into the sky. Elevators lift people fifty floors. Nobody is strong enough to do that with just their arms. So how do you think they do it?”

Take guesses. Then: “Thousands of years ago, people invented six tools so clever we still use them every single day. Today we are building one of them.”

Quick tour of the six: lever (seesaw), wheel and axle (doorknob), inclined plane (ramp), wedge (knife), screw (jar lid), and pulley, which is ours today.

The Build

Materials per student: cardboard, easel, self-adhesive strips, double-sided tape, 3 bobbins, mini cup, string, pennies or weights, hole punch.

  1. Attach the cardboard to the easel using the self-adhesive strips.
  2. Stick three pieces of double-sided tape to the cardboard in an upside-down triangle.
  3. Press the flat side of one bobbin onto each piece of tape.
  4. Punch a hole in each side of the mini cup, run the string through, and tie it off just above the cup to make a handle.
  5. Route the string through the bobbins, starting at the far left: over, under, over.
  6. Add pennies to the cup and pull gently on the free end of the string to lift it.

Productive struggle moments

Our STEM projects are designed so that participants get it wrong before they get it right. You will observe your students struggling as they attempt to create their own STEM projects. This process is an empowering experience, building perseverance, frustration tolerance, and growing overall confidence! With your support, students will step out of their comfort zones to think, build, and problem-solve for themselves.

  • Peeling double-sided tape tests fingernail patience. Suggest folding a corner first, then step back.
  • Tying the knot to the cup (see Knot Tying Guide) may take three tries. Three tries is the point.
  • The over-under-over route is easy to get backwards, and a wrong route often still works, just differently. That is not an error to fix. It is data for the investigation below.

When frustration shows up, narrate instead of fixing: “You are doing the hard part right now. What is one thing you could try differently?”

The Investigation

The original step 7 is the whole lesson: reroute the string and see what changes. Structure it:

Predict: “If I route the string ___, then the cup will ___ because ___.” Test at least two routes: over-under-over versus over-over-over, or two bobbins versus three. Pull from different directions: down, sideways, at an angle. Measure (grade 3+): how many pennies can each route lift before the pull feels hard? Pennies are a built-in measurement unit. Explain the mechanism (grade-band it):

  • K–1: I pull the string down, and the cup goes up. The pulley flips my pull around.
  • 3: A pulley changes the direction of a force. Pulling down is easier for our bodies than lifting up, so the machine makes the job easier even though the cup weighs the same.
  • 4: More pennies means more weight pressing the string against the bobbins, which means more friction. That is why a full cup is harder to lift even with the pulley helping.

Honest physics note for teachers: a fixed pulley like this one changes the direction of the force rather than shrinking it. The win is that pulling down (using your body weight and gravity) beats hauling up. Avoid telling students the pulley makes the cup “lighter.” Let them discover what it actually does, then name it.

Great “failure” to expect: some routes will jam, or the cup will tip and spill weight. Ask: “Where is the string getting stuck? What could you change about your route?” Jammed pulleys are friction made visible.

Skills in Practice

  • “I predict this route will ___ because ___.”
  • “I observed the cup ___ when I pulled ___.”
  • “My evidence shows the pulley changes ___.”
  • “Next time I would route the string ___ because ___.”

Real-World Connection

Flagpoles, blinds, cranes, elevators, rock-climbing gear, and stage curtains all run on pulleys. Ask: “Where could a pulley help you at home?” (Lifting a basket to a bunk bed, raising a bird feeder, hauling toys upstairs.) For grade 3+, connect to compound machines: a crane is a pulley plus a lever plus a wheel and axle, all working together.

Evidence of Learning

  • K–1: Student demonstrates the pulley and states “I pull down, the cup goes up.”
  • 3: Student names what the pulley changed (the direction of the force) and which of their routes worked best, in one or two sentences.
  • 4: Student explains in 2 to 3 sentences why more pennies made lifting harder, using the words force and friction.

Vocabulary

  • simple machine: a tool that changes the size or direction of a force to make work easier.
  • pulley: a wheel with a rope or string around it that changes the direction of a pull.
  • force: a push or a pull.
  • friction (grades 3+): a force that resists motion when surfaces rub, like the string against the bobbins.

Required Materials

  • 3 plastic bobbins or spools
  • 1 cardboard
  • 1 easel (optional)
  • 3 double-sided foam mounting tape
  • 1 mini paper cup
  • 2 ft string
  • pennies or other small weights
  • hole punch

Optional STEM Activities

Resource 1

Meet the Project Developer (all grades, 5 minutes, high value). Show the video of Emma, the high school student and Rosie Innovator who designed this project. Her line, that understanding the world more deeply helps us come up with better solutions to our problems, is the mission of the whole kit in one sentence. Students respond powerfully to learning that a kid designed the thing they just built. Ask: “What would YOU design to make a job easier?”

VIDEO

Resource 2

Simple Machine Scavenger Hunt (grades K-5). Teams hunt for the six simple machines in the classroom, school, or home (scissors are levers AND wedges; the pencil sharpener hides a wheel and axle; the ramp by the front door is an inclined plane). Teams present their finds. This is the “obtaining and communicating information” practice, and it turns the whole building into the lesson.

Resource 3

Rosie Reads: Secret Engineer (grades 2+). The story of Emily Roebling, who saved the construction of the Brooklyn Bridge. Pairs the machine with the engineer and the build with a woman in STEM whose work students can still walk across today.

Rosie Reads Banner and book cover of Secret Engineer
,
Engineering

Rosie Reads Secret Engineer

Follow the adventures of Emily Roebling - the woman who saved the construction of the Brooklyn Bridge!

Resource 4

Career Spotlight: Structural Engineeer

Every crane on every construction site is a pulley system with an engineer behind it. Structural engineers design the machines and frameworks that lift, hold, and move enormous loads safely, using exactly the force-direction thinking students practiced on the bobbin wall. The pathway starts with building and asking why things stand up: math and physics classes, a civil or structural engineering degree, then site work alongside experienced engineers.

Roma Agrawal is a structural engineer who spent six years helping design The Shard, the tallest building in Western Europe, including the spire at its very top. She also writes books that explain how bridges, buildings, and everyday machines like pulleys actually work, because she believes everyone deserves to see the engineering hiding in plain sight.

Show the class (2 to 3 min): Mission Unstoppable, Season 6 Episode 4 (“Coasters, Crystals, and Chemical Engineering”), shows the physics that make roller coasters fun, and Season 3 profiles a structural engineer who makes buildings as responsive as humans. Segment clips: https://www.youtube.com/@CBSUnstoppable (search “roller coaster” or “structural engineer”).  Preview before showing.