Building a Simple Pulley System with String and a Spool

A simple pulley turns a small classroom investigation into a practical lesson about force, motion and mechanical advantage. With a wooden or cardboard spool, strong string and a lightweight object, children can see how changing the direction of a pull helps lift a load.

This activity suits primary classrooms, homeschool spaces and family learning at home. It uses inexpensive materials, supports hands-on STEM learning and can be adjusted for children in early years through to upper primary. In Australia, it can connect naturally with the Australian Curriculum through science inquiry, measurement, design and technologies.

Materials And Preparation

Gather a spool with a central hole, smooth string or cord, a support point, scissors, tape and a small load such as a basket, cup or fabric bag. A cotton reel, large craft spool or clean thread spool can work well, provided it spins freely and has no sharp edges. Choose a load that is light enough for the string and support to hold securely.

A doorway frame, sturdy shelf, low beam or classroom stand can provide the anchor. In a Melbourne or Sydney classroom, a portable science stand may be easier to manage than attaching equipment to a wall. Keep the activity on a clear table or floor area, and use a tray beneath the load to contain loose objects. For a related visual exploration of shape and space, teachers can pair the activity with Light Cube geometry.

Building The Pulley

Thread the string through the centre of the spool, then secure both ends to a firm support so the spool hangs between them and can rotate. The string should sit in the spool’s groove, if one is available. Check that the spool turns smoothly instead of rubbing against the support, as friction can make the system difficult for young children to operate.

Tie one end of a second piece of string to the basket or load. Pass this string over the rotating spool and leave the free end within easy reach. When a child pulls down on the free end, the load should move upwards. For a first demonstration, use a soft toy or a few blocks rather than anything breakable.

Exploring Force And Motion

Explain that the spool acts as a wheel, while the string works like the rope in a traditional pulley. The pulley changes the direction of the applied force: instead of lifting upwards, a child can pull downwards. This arrangement does not necessarily reduce the total force needed, especially when the spool is small or rough, but it can make lifting more convenient.

Ask children to predict what will happen when the load becomes heavier, the string becomes longer or the spool is replaced with a larger one. They can compare a free-hanging pulley with a fixed spool and record whether the load rises smoothly, jerks or stops. These observations introduce friction, gravity, tension and mechanical advantage without requiring complex formulas.

Measuring The Results

Mark the string at regular intervals with removable tape. Children can count how many pulls or centimetres of movement are needed to raise a basket to a particular height. A ruler, stopwatch and simple recording sheet turn the model into a measurement investigation. Older students can calculate the distance pulled compared with the distance the load travels.

Change one variable at a time to keep the test fair. For instance, use the same load while comparing cotton cord with smooth nylon string, or keep the string unchanged while testing an empty and full basket. In Brisbane or Perth, the activity could also be moved outside on a calm day, provided the support is stable and the equipment is protected from wind and direct heat.

Extending The Learning

Children can design a miniature crane, flag raiser, well or lift using recycled cardboard, craft sticks and paper cups. They might add a second spool and compare a fixed pulley with a moving pulley. This invites discussion about cranes at construction sites, sailing boats, theatre equipment and lifting systems used in warehouses around Australia.

The experiment also supports literacy and communication. Students can label a diagram, write instructions, explain a prediction or present their findings to a partner. Teachers looking for additional hands-on education ideas can browse JAMB learning resources for activities that complement practical investigation, construction and problem-solving.

Safety And Classroom Practice

Supervise children closely, especially when string is cut, tied or looped around a support. Keep cords short enough to prevent tangling, never place them around a child’s neck or wrist, and avoid attaching the apparatus to unstable furniture. Inspect the spool for splinters and discard damaged cord. Australian schools should follow their workplace health and safety procedures, including local rules for equipment, supervision and risk assessment.

Use materials that are suitable for the child’s age and follow product instructions when combining commercial manipulatives with homemade parts. In family settings, an adult should handle elevated supports and heavier loads. The same principles can lead into sensory learning: a nearby sand and water table can provide a supervised setting for moving cups, scoops or small containers with a pulley-inspired design. These experiences help children connect physical movement with observation, language and purposeful play.