1976-02-18
1977-11-22
Grieb, William H.
G09B 2304
Patent
active
040589129
ABSTRACT:
The invention provides didactic apparatus for use by young children in ascertaining the volume of solid structures built from unit cubes or blocks, and broadly comprises a square base plate and two rectangular walls connected at right angles and mounted on said base plate so as to be in planes parallel with but spaced from two adjacent sides of said base plate. Said base plate and walls are each marked with grid lines each square of which is of unit dimensions and the grid lines of the base plate externally of said walls are consecutively numbered from the juncture of the walls. The walls, at least, are transparent and horizontal grid lines thereon are numbered consecutively from the bottom.
REFERENCES:
patent: 1880130 (1932-09-01), Goldbach
patent: 2472439 (1949-06-01), Rogers
patent: 2977688 (1961-04-01), Redey
Welch Scientific Co. Catalog, p. 39, Models 7589, 0129, 0133, .COPYRGT. 1965, received in PTO Oct. 1965.
Drucker William Anthony
Grieb William H.
Philograph Publications Limited
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