The Elbe cards have been planned in consultation with practising and retired ~ but widely experienced ~ maths teachers. Their style has been developed by professional graphics designers with advice from the printing profession.
Points to note. The cards is thick ~ 450gsm ~ and lightly coated and polished ~ technically called silk finish. They will crease if maltreated, but will withstand a great deal of sensible handling for quite some years. They have not been laminated with plastic film ~ handling with clean hands is anticipated. They do not shuffle and handle with the slipperiness of playing cards, but the cost of producing them is about three times as much.
The size selected is the same as that of a standard credit card ~ slightly smaller than the 'Bridge' playing card size ~ large enough to be handled with ease. Small cards take up less space on the table ~ but are a fiddle to handle. We would suggest that when using them a soft surface makes for easier picking-up ~ the fingers can get under the edge of the card. This is not practical at school, but at home a cloth is a good idea.
There is evidence that some people find it visually more comfortable to reduce the contrast of printed matter. We have done this by using a very light blue background tint, and by reducing the intensity of the black ink. The rounded corners are another move towards user-friendliness. It is also important to note that square corners quickly show signs of wear and grubbiness. Rounding them off helps ~ considerably ~ to prolong overall appearance.
There is a nod towards playing cards by introducing thumbnails in the top left corner. A mini sketch of an appropriate number of dots is also included, as is the relevant word. We did debate for some time as to whether all this added confusion and we eventually decided it was a useful addition, which also served to create a clear base to the cards. Yes, these reminder shapes are small ~ we opted for less distraction.
The shape of the numbers involved considerable consultation of suitable typefaces. Many styles failed on one or two small counts of clarity. A six must look different from a reversed nine ~ a one needs a slight lead-in-tick. The English seven does not have a cross bar. We also recognize that some styles are widely different. (We plan to make a crossed 7 available as an extra alternative ~ eventually.) A great deal of research has already been done in this area by the educationalist Rosemary Sassoon, in collaboration with tyeface designer Adrian Williams. We have happpily adopted some of their typefaces for all our educational work.
The Elbe series of BusyBusy cards ~ and their purpose ~ is fully described on a separate page .