Saltire Software

Geometry Angle Problems

This collection of puzzle books dives into the intriguing world of polygons, challenging your understanding of heptagons, octagons, hexagons, and pentagons.

Each problem in these books can be solved by applying a couple of simple geometric facts. However, how and where to apply them can be challenging.

On the Sensations of Tone

An electronic adaptation of the masterpiece on the physiological fundamentals of music theory by Hermann Helmholtz.

Embark on an extraordinary adventure as you dive into the text, immersing yourself in a captivating world of auditory wonders. Unleash your creativity by actively recreating the ingenious experiments depicted within its pages.

Interactive Euclid's Elements

Few books in history have affected the development of mathematical, scientific, and philosophical thought more than Euclid's Elements.

The propositions and figures in the first 4 books form the geometric core of the work. We have turned the 127 original black and white static figures into colorful, interactive apps that illustrate the propositions dynamically.

What translator Sir Thomas Heath calls "one of the noblest monuments of antiquity" is newly dressed for the 21st century.

24 Whimsical Clocks: and the mathematics behind them

Each chapter in this eBook begins with a weird clock, and discusses the mathematics that turns up in its wake. Most, but not all, of the clocks describe curves, so much, but not all, of the mathematics involves the geometry of curves.

Striking interactive visual proofs of intriguing results will whet your appetite to explore this mathematics yourself.

This book will delight anybody with an interest in mathematics, regardless of how much or how little formal education they have in the subject.

Common Core Nuggets

Teachers are searching through an overwhelming mountain of information labeled "Common Core" to find materials and activities that will be helpful in implementing the standards with their students.

This group of apps consists of simple, short, and focused interactive demonstrations and explorations that are designed to help students master the important concepts of a single standard.

Available here in iOS, Android, TI-NSpire^TM, and Web editions.

Electronic Atlas of the Four Bar Linkage

Our Electronic Atlas of the Four Bar Linkage for your iPad combines the ease of browsing of a physical book with the flexibility of a computer program.

All diagrams from our paper Atlas are present, but in interactive form. You can animate the diagram, you can change the lengths of the links and placement of the coupler point to examine intermediate forms.

Euclid's Muse

Euclid's Muse is our website with hundreds of free interactive mathematical apps. The apps run in your browser on your computer, tablet or smart phone.

Geometry Expressions users can post their own apps to Euclid's Muse.