Educational device

Details Educational device Educational device

1994-09-23

1999-09-21

Hirsch, Paul J.

Education and demonstration

Mathematics

Arithmetic

434188, 434209, G09B 130, G09B 1902

Patent

active

059545097

ABSTRACT:
An educational device having a base page, which may be transparent and multiple intervening transparent pages and a structure to hold the multiple intervening transparent layers in registration in which the base layer has a set of problems which are modified by each succeeding overlying layer and in which the numbers are formed by using seven segment blocks similar to those used by light emitting diodes or liquid crystal displays for forming and modifying the numbers and the indication of the operation to be performed if formed by using one to four segment blocks.

REFERENCES:
patent: 2560130 (1951-07-01), Russo
patent: 2600084 (1952-06-01), Svensson
patent: 2751690 (1956-06-01), Cohen
patent: 3172599 (1965-03-01), Passerini
patent: 3405460 (1968-10-01), Michaelson
patent: 3432943 (1969-03-01), Merkel
patent: 3531877 (1970-10-01), Miller
patent: 3541702 (1970-11-01), Cohen
patent: 3768177 (1973-10-01), Thomas
patent: 4185401 (1980-01-01), Smathers
patent: 5110295 (1992-05-01), Concra

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