The Children's Discovery System by Mattel was released in 1981 for about $120. Mattel refers to it as a computer and indeed has a design similar to a computer. Children's Discovery System has a 2.5 inches length cartridge slot that takes learning modules.
As Children's Discovery System's box claims, the learning modules are Math, Music, Art, Word Fun and Arcade and learning modules that would be released afterwards would be "Science, History, Health, Geography, Economics, Arithmetic, Fractions and Decimals, Spelling plus Surgery and Sports and many more!". However, the console discontinued in 1984.
The console box includes the Math learning module cartridge, activity book and overlay of the keyboard and a 120 page manual too. The price of the other learning modules was $21 each, $2.50 was the price of an activity book and $2.25 of the leaning module overlay. Each learning module activity book has a different color and a different child portrait at the front page.
The learning modules-cartridges that are know to be released are: Math I, Arcade Action I, Words I, Art, Music, Words II, Arcade Action II, Memory and Logic, Geography I, Foods, Fractions I, Fractions II, Science I, Presidents, Computer Programming, Spelling Fun.
The console has also a small LCD screen with only a grid of 8-by-2 text possible and a speaker. The power source is 6 AA batteries. There is also an AC adapter cable socket. Adapter and batteries didn't included inside the Children's Discovery System's box.
Interesting facts about Children's Discovery System:
There is no saving mechanism
There are similarities with Mattel's Intellivision
Some learning modules games will turn of after 2 minutes of no activity (not any key pressed) in order to save power
Below you can watch a 1980 commersial of Children's Discovery System: