Have you ever heard of a rekenrek?
It is much like a abacus, only it is used differently. It can be used to teach number sense.
My weekend project was to make these for my small math groups. The idea came from the book Number Sense Routines. Students learn to recognize numbers in relation to 5 and 10 by sliding the beads across the pipe cleaner. See the link at the end of this post for a complete guide to using the rekenrek.
Here is a sample of the ones I made with materials and directions to follow:
pony beads (10 of two different colors for each board) - White and red are traditional
foam board (I used 4x6 squares cut from 8 by 6 foam)
pipe cleaners (2 per board)
Hole punch four holes into the foam board about an inch square from each corner.
String 5 red beads and 5 white beads on a pipe cleaner and insert the ends into the holes long ways.
Again string 5 red and 5 white on the other pipe cleaner and insert the ends into the remaining holes. Twist tie the ends of the pipe cleaner like so:
The following website has a great book about how to use the rekenrek. http://catalog.mathlearningcenter.org/files/pdfs/URVM_0610.pdf