73529782
Apr 1, 1985
Jul 15, 1986
TEACHING APPARATUS, NAMELY KITS CONTAINING STORAGE CASES AND MANIPULATIVE PIECES USED TO ILLUSTRATE MATHEMATICAL RELATIONSHIPS AND CONCEPTS, AND EDUCATIONAL DEMONSTRATION APPARATUS HAVING MOVING PARTS WHICH ILLUSTRATE TRIGONOMETRIC RELATIONSHIPS; AND EDUCATIONAL PRERECORDED VIDEO TAPES
Electrical and Scientific Apparatus