Unroll Pi
Launch this tool in a distraction-free environment optimized for classroom instruction.
About
Unroll Pi is a beautiful, interactive simulation that transforms the abstract concept of Pi into a physical reality for your students. By unrolling a circle along a ruler, they can visually and tangibly connect a circle's diameter to its circumference. It takes the guesswork out of the formula and replaces it with an intuitive discovery moment that sticks.
STEM connections
This tool blends mathematical proof with interactive technology, giving students a tactile way to explore geometry in real time.
Mathematics: Proportional Reasoning
Students analyze the dynamic data table to discover that the ratio of circumference to diameter remains perfectly constant.
Technology: Data Visualization
The app automatically records and updates trial data, helping students immediately see how changing one variable impacts the digital model.
Art: Visual Pattern Recognition
By leaving a vibrant trail along the digital ruler, the simulation paints a clear visual picture of a geometric relationship.
What students will learn
Explain why the ratio of circumference to diameter is constant for all circles.
Estimate the circumference of a circle visually using its diameter.
Define Pi based on physical measurements rather than just a memorized formula.
Using it in class
Use this as a powerful hook before diving into foundational circle geometry or radian measure. It works brilliantly as a whole-class demonstration on the interactive whiteboard, or for students working in pairs to build their own proofs.