Making slime to explore non-Newtonian fluids
Slime looks like a glossy, stretchy material, yet its behaviour changes with the way it is handled. A gentle push can make it flow, while a sharp jab briefly resists and breaks apart. That contrast makes homemade slime a practical entry point for studying non-Newtonian fluids, substances whose apparent viscosity changes under stress rather than staying constant.
Water and honey have relatively predictable viscosity. Slime behaves differently because its liquid-solid boundary is controlled by a network of long polymer chains. Children can see, feel and describe this change directly, giving abstract ideas such as shear, friction, pressure and reversibility meaning beyond a diagram or textbook definition.
For Australian learners, the activity fits naturally into kitchen-table science, homeschool co-ops and classroom projects. Melbourne’s changeable weather, Brisbane’s humidity and Perth’s dry summers offer different conditions for storing materials, while indoor work on a tray remains comfortable across the country. Washable surfaces and simple cleanup are familiar household priorities, making the experiment easier to incorporate into everyday routines.
Science teaching in Australia can connect the investigation to the Australian Curriculum’s treatment of material properties, forces and evidence-based explanations. A useful inquiry moves beyond making the mixture: learners change one variable, predict what will happen, record what they observe and justify the pattern using terms such as viscosity, shear-thinning and suspension. The result is playful but also suitable for structured assessment.
| Feature | PVA slime | Cornstarch mixture |
|---|---|---|
| Structure | Network of polymer chains | Solid particles suspended in water |
| Under slow force | Flows and stretches | Flows slowly |
| Under fast force | Often splits or feels briefly firm | Resists and can feel solid |
| Main cleanup issue | Sticky residue | Excess dry powder |
Prepare a controlled batch
Use PVA craft glue, warm water and plain sodium borate under adult supervision. Mix 120 mL glue with 120 mL warm water, then add colour if desired. Dissolve one teaspoon of borax in 120 mL warm water and stir it slowly into the glue. The borax should be fully dissolved before contact with the glue. Knead the mixture for two to three minutes, then leave it to rest so the polymer network can develop.
The key ingredient is the interaction between borate and PVA. Borate ions form temporary connections between long glue molecules, creating a network that traps water. Pulling the slime apart breaks some connections; pressing it brings them back together. This reversible structure explains why the material can feel runny, stretchy or rubbery within seconds.
Keep batches in labelled containers and record the quantities used, because small changes in water or borax alter the result. A sticky mixture can be loosened with warm water a teaspoon at a time, while an overly firm one can be softened with a little extra glue. Use craft glue rather than general-purpose adhesive, and avoid products containing added fragrance or enzymes.
Observe force and flow
Test the finished slime with several actions rather than judging it from one movement. Push a finger slowly across the surface, jab quickly, lift a spoonful and let it fall. Roll part of it into a ball and press the ball between two palms. Predict the response before each action, then repeat every test on an equal-sized sample of the cornstarch mixture.
These actions reveal shear-thinning behaviour: increasing the rate of force generally lowers the slime’s resistance and allows it to flow more readily. Slowness makes the material stretch and ooze, while a rapid impact can split it or make it feel momentarily firm. Pressure and friction become useful terms when students describe what their hands are doing rather than treating “hard” and “soft” as fixed properties.
More reliable evidence comes from controlling the amount of material, the depth of the sample and the size of the container. Learners can time how long each spoonful takes to move down a shallow slope, compare a ball’s shape before and after squeezing, or sketch the flow pattern. Repeating each test three times separates a consistent material response from an accidental push.
Contrast slime with oobleck
To make a direct comparison, mix two parts cornstarch with one part water in a second bowl. Begin with the water, then add more starch until the mixture holds a shape but still moves slowly when tilted. This cornstarch suspension, often called oobleck, feels firm under a fast jab yet relaxes into a liquid when the force stops. Its response is the reverse of the PVA slime’s.
The difference begins with structure. PVA slime is a polymer network, while oobleck consists of solid particles suspended in water. A quick force crowds the particles together so they resist movement; a slower push lets them rearrange and flow. Equal masses of both mixtures can be tested on the same plastic ramp, with learners recording distance travelled and changing only the material. The contrasting results show why the rate of stress matters, not merely the presence of a substance.
Build an Australian curriculum investigation
Broader classroom planning can draw on the Roylco learning supplies catalogue for craft papers, science kits, educational manipulatives and hands-on project ideas. Teachers, parents and homeschoolers can compare those classroom-ready resources with materials commonly found in Australian stationery and craft aisles, helping them plan within local budgets and the reuse practices common in many Australian homes and classrooms.
Within an Australian lesson, begin with a phenomenon such as a quick poke feeling solid while a slow pour flows. Students then build an explanation, test a variable and communicate their evidence. Photographs, labelled diagrams and short oral explanations can all contribute, so participation does not depend on advanced writing. Scientific vocabulary develops most effectively when it grows directly from the observations.
Assessment can use a claim-evidence-reasoning sheet: each learner states that viscosity changes under stress, cites two observations and explains what happened to the polymer network or particle arrangement. A practical extension is to design a material for a specific job, such as a slow-flow display putty or a shock-absorbing model, and defend the design with test data. This connects play, design and science within one coherent task.
Manage safety, waste and classroom routines
Safety planning should match the setting. Suppliers of educational products sold in Australia must meet the Australian Consumer Law’s requirements for safe products and adequate information. Schools also follow state or territory work health and safety duties, chemical-handling procedures and risk-assessment rules, which can differ across jurisdictions. Keep original labels and safety data sheets for prepared classroom materials, and check local policies before using homemade mixtures.
During the activity, check for allergies and skin sensitivities, supervise younger children closely, and keep slime and oobleck away from eyes, mouths and food-preparation areas. The cornstarch mixture is difficult to wash from hair and clothing, while borax-based slime should never be tasted. Afterward, wash tools with warm soapy water and dispose of small batches according to ingredient labels and school wastewater guidance. Teachers comparing further resources can consult Jamb classroom resources while connecting practical investigations with classroom routines. Careful preparation keeps the investigation safe, reproducible and engaging.