The Gilbert U-238 Atomic Energy Lab was a children's science kit introduced in 1950 by the A.C. Gilbert Company, the same company famous for its Erector Sets. This kit sold from 1950 to 1951 for $50 which was very expensive for a toy at that time. Often referred to as “the world’s most dangerous toy,” it is both unusual and controversial, primarily because it includes real radioactive materials (using a Geiger nowadays shows that these radioactive levels are similar to the levels of cosmic radiation that we are exposed to on Earth).

The Atomic Energy Lab was marketed as an educational toy designed for children aged 12 and up, and it came in a large box that contained materials, working instruments, and models. Four small samples of uranium ore and disks of alpha, beta and gamma-ray irradiated material are what make the kit infamous. A working Geiger counter could detect the presence of radioactivity. The Wilson cloud chamber allowed the visualization of alpha particles emitted by radioactive materials. The kit also contained models that helped children visualize atomic structures and understand the principles of atomic energy, and a “spinthariscope”, used to observe scintillations (tiny flashes of light) that indicated alpha particle decay emitted from the radioactive sources that came with the kit. The Lab also came with a detailed instruction booklet on how to perform various experiments, how to work the instruments, how to build a cloud chamber, and even “games” children could play such as “hide and seek” – you hide the radioactive source while your friend seeks it out with the Geiger counter. Also included was a coupon that could be mailed in to receive more radioactive samples from the toy company.