Abstract: 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.

Abstract: 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.