Educational device
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United States of America Patent
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-
Sep 21, 1999
Grant Date -
N/A
app pub date -
Sep 23, 1994
filing date -
Sep 23, 1994
priority date (Note) -
Expired
status (Latency Note)
Importance
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.
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