Chris Tisdell develops new geometry tool

Chris Tisdell has developed a new device that could replace a common tool which has long been a staple in classroom maths kits.

Many learners and teachers struggle to use compasses effectively and safely in geometry – they are often tricky to operate, can lead to inaccurate drawings, and have the potential to be dangerous.

Professor Tisdell saw value in reconsidering the role of the compass in the learning and teaching of geometric constructions, identifying a need for a more user-friendly apparatus that can be used by students and teachers more safely, and with enhanced precision.  

"When I was at school, I found compasses difficult to use. Turns out I wasn't alone, and recent surveys indicate 86% of students see value in alternatives”, said Prof Tisdell. “Compasses are difficult, inaccurate, and dangerous; and so I've spent the past year designing this new tool that replaces the compass in high school geometry."

Introducing the circle arc tool (pictured). Reminiscent of a pac man silhouette, the circle arc features on a plastic sheet template and aims to offer a safer, more efficient and effective alternative. 

“Learners and teachers can add value to their classrooms by using it, in conjunction with a straightedge, to establish the well-known constructions seen in geometry curricula around the world”, said Prof Tisdell.

The new tool is currently being patented and will be available from Officeworks, Amazon and other retailers later this year.  
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Read Professor Tisdell’s research paper on the circle arc, written with the assistance of UNSW Maths student David Bee Olmedo. 

Watch the circle arc in use in this video by Prof Tisdell.