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Class Information
Number: 434/328
Name: Education and demonstration > Question or problem eliciting response > Correctness of response indicated to examine by self-operating or examinee actuated means > Involving heat or chemical reaction
Description: Subject matter wherein the correctness of the examinee"s response is revealed by means of thermal energy or a chemical transformation.
Patents under this class:
| Patent Number |
Title Of Patent |
Date Issued |
| 6879805 |
Test form having a removable opaque layer, and method and apparatus for printing on the form |
Apr. 12, 2005 |
| 6152449 |
Combined sticker and invisible ink game |
Nov. 28, 2000 |
| 5217231 |
Power of observation invisible ink game |
Jun. 8, 1993 |
| 5188871 |
Authenticatable security paper |
Feb. 23, 1993 |
| 5160266 |
Mix and match invisible ink game |
Nov. 3, 1992 |
| 5011445 |
Color memory toy set |
Apr. 30, 1991 |
| 4787852 |
Multicolor interactive notepad |
Nov. 29, 1988 |
| 4781595 |
Visual design and character formation composite |
Nov. 1, 1988 |
| 4744113 |
Toilet training aid and method |
May. 17, 1988 |
| 4702497 |
Method of encoding a symbol or message on a plastic material and an article on which a symbol has been so encoded |
Oct. 27, 1987 |
| 4631203 |
Latent imaging and developer system |
Dec. 23, 1986 |
| 4514177 |
Invisible ink quiz game |
Apr. 30, 1985 |
| 4360548 |
Self-contained covert image |
Nov. 23, 1982 |
| 4337051 |
Self-scoring test with non-disclosed key |
Jun. 29, 1982 |
| 4198445 |
Latent image printing and development |
Apr. 15, 1980 |
| 4188431 |
Latent image printing and development |
Feb. 12, 1980 |
| 4139965 |
Device using coated paper and chemical reactive marker |
Feb. 20, 1979 |
| 4111462 |
Latent, sensitizing ink |
Sep. 5, 1978 |
| 4084332 |
System for visual communication |
Apr. 18, 1978 |
| 4051283 |
Printed sheets containing concealed images and method and materials for preparation and visual development of same |
Sep. 27, 1977 |
| 4038761 |
Element and method for teaching with liquid crystals |
Aug. 2, 1977 |
| 4028118 |
Thermochromic materials |
Jun. 7, 1977 |
| 3990156 |
Constructed response method with invisible answer indicator to prevent cheating |
Nov. 9, 1976 |
| 3979550 |
Pre-printed latent image spirit duplicating masters |
Sep. 7, 1976 |
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