TeachEngineering
Teach Engineering: Discovering Phi: The Golden Ratio
Students discover the mathematical constant phi, the golden ratio, through hands-on activities. They measure dimensions of "natural objects"--a star, a nautilus shell and human hand bones--and calculate ratios of the measured values,...
Texas Instruments
Texas Instruments: At a Snail's Pace for the Ti 73 Explorer
It is hard to imagine a way to mathematically describe a spiral. Spirals are commonly seen in nature. There are a number of different types of spirals. Some interesting examples include the spiral arrangements of scales in pine cones,...