An apparatus and method for teaching mathematics to children is disclosed.
In one embodiment, the apparatus comprises a flat, ruler-like rod having
expressed on one face a vertically arranged base-ten number line; lips at
the ends of the rod; spaced-apart grooves on the back face of the rod; and
an attached sleeve sized to snugly accommodate the rod and to slide
thereon while indicating respective numerals on the number line. The
sleeve is prevented from being separated from the rod by the lips on the
rod. The sleeve has a transparent portion to frame individual numerals on
the number line as the sleeve slides along the rod. On the inner portion
of the reverse side of the sleeve a projection made of flexible material
strikes the interior portion of individual grooves as the sleeve slides
along the rod. In operation, the apparatus provides an audible and felt
"click" as the sleeve passes over each numeral. A method is described for
using the apparatus to teach elementary school children math concepts
using a vertically oriented number line.
