The Brand "Science Fair" was actually owned by Tandy which of course actually was Radio Shack. They had a microcomputer trainer with a similar design. On the bottom it says in tiny print: made in china. I have no definitive date on when these were made. It appears to be a mid 1980s product just from the color scheme and the condition of the hardware. For what it's worth, Tandy trademarked the brand "Science fair" in 1970. More here.
They worked but were totally inferior to other available gear. You can get a breadboard and jump wires cheap enough to call it a toy. Btu if you want to go all out, the Denshi block-type units like the Gakken EX-System were reissued in 2002, so they are available but very pricey. See below: