10cm Standard Numdrum

The Numdrum has been designed to specifically address deficiencies in commonly used models of the numberline.

Drawing the number line literally as an annotated line does not strongly convey the decimal structure of our counting system, except in the periodicity of the notation. It also becomes unwieldy to enumerate more than about 20 number positions in a straight line.

In contrast, the Numdrum presents an extended numberline (from 0 to 139) in a very compact form by printing the numbers in a spiral path around a small cylinder.

The number square is an improvement on the straight line representation. It is compact, and its rows of ten digits can help to convey the decimal concept, but the numberline is discontinuous; on reaching the end of a row, the student must move to the beginning of the next row, which is a potential source of errors and confusion. Also, the fact that the numbers neatly stop at 99 can cause less able students conceptual difficulties with the transition to 3 digit numbers. Finally, the numbers increase as you move down the grid, which is contrary to the everyday notion that up equals bigger.

To address these deficiencies, the Numdrum number line increases in value as it winds up the cylinder. It is a continuous spiral, and there are exactly ten digits in one revolution so skipping up or down by one turn of the spiral represents a tens change, and rotating one digit left or right represents a units change.

The yellow spiral band against the light blue background emphasizes the flow of the number line and provides contrast. This may be of particular value to students with dyslexia.

The Numdrum is supplied with a clear plastic sleeve that has been marked so that it can serve as a cursor. The Teacher's and Cursor Activities Notes provide more information and suggestions for use including a description of the various learning activities that can be built around use of the cursor.

Specifications

• Dimensions: 10.2cm x 3.6cm
• Material: ABS Plastic

A cursor sleeve is supplied tucked inside the tube.

Note: A printed copy of The Teacher's and Cursor Activities Notes is only supplied with the Classroom Set, however, you can download and print your own copy here.

Reviews and Comments

“Numdrums have proved very useful and the children enjoy using them”
Whatfield School, Suffolk

“An inspired invention.....helping primary children get a firm grasp of number patterns”
Victoria Neumark, The Times Educational Supplement

“The Numdrum seems to knock down barriers that children may experience when getting to grips with addition and subtraction. . . Above all children actually enjoy using it.”
Liz Pumfrey, NRICH, Cambridge Autumn 2002

“The most innovative number teaching tool we have seen for years”
www.mathmagic.org

“We find the children enjoy using them because the anxiety of where to go at the end of the line (in the number square) has been removed”
Ruth Cullingworth, Year 3 teacher

“The lower ability children have found them much easier to use – our only problem is collecting them at the end of the lesson because the children are having too much fun to want to give them back!”
St. George's Middle School, Dersingham

“We use Numdrums in our year 3/4 class. The children are very at ease with them and enjoy using them. They are a very simple and effective aid to number work.”
J. Wood, (Head); Cookley & Walpole Primary School, Suffolk.