A retired teacher has invented and patented a counting machine designed to help dyslexics in number work.
Celia Stone, 63, of Guiseley, who taught and wrote books for children with dyslexia, created the Addacus after requests from teachers for resources to help children who struggled with maths.
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Grandmother Mrs Stone found financial backers, drafted in members of her family and church to help and took out a bank loan to turn the idea into reality.
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Now she and husband Brian, spend their retirement selling and marketing the Addacus from their home and tour the country to promote and run training sessions about her invention.
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"I felt the idea for Addacus dropped into my lap but I cried and cried when I discovered it was going to cost 30,000 to manufacture," said Celia, who fled Zimbabwe in 1980 with her husband and three children because of civil unrest.
She came to the UK with no more than 500.
The grandmother of seven, who taught at Woodhouse Grove, Apperley Bridge, refused to give up and persuaded veteran Yorkshire businessman Brian Greenwood to invest.
Members of her congregation at Guiseley Baptist Church helped with the design and building of the prototype, and her family were drafted in to compose original songs which are part of the Addacus teaching resources.
Before going into production the machine was researched, tested and modified at the Centre for Design Research at Northumbria University.
Celia said: "It has not been profitable. We had to borrow considerable sums and we have to pay off a bank loan.
"Brian and I don't draw a salary but it is for the love and hopefully one day we will recoup some money.
"I want to make a difference to people's lives. I don't consider myself an academic. I'm a coal-face kind of person."
Research shows that up to 60 per cent of people with dyslexia also struggle with numbers and even simple mathematical concepts – in a condition known as dyscalculia
But the Addacus also has potential in helping all children learn to understand number concepts in a fun, multi-sensory and tactile way, said Celia.
Using her years of experience as a teacher of dyslexic children she designed the Addacus to look like a cash till with three posts sticking upwards, similar to a traditional abacus.
Specialised clear cubes reinforce place value, demonstrating practically the way the decimal number system works.
As each post only accommodates nine cubes pupils learn place value by operating this 'calculator' themselves and number dials add recognition of each written number.
Along with the machine itself Celia and former teaching colleague Myra Nicholson designed and wrote a whole resource pack to work alongside the Addacus, including activity sheets, work books, songs, stringalongs and number strips.
Celia said: "The whole thing about the Addacus is that is a discovery method. It provides a highly structured, multi-sensory course, with small steps.”
The Addacus is now being used all over the country in schools from Essex to Newcastle, said Celia.
For more information go to www.addacus.co.uk.