I recently purchased a Geiger counter kit from Goldmine Electronics. I soldered everything together; attaching the Geiger tube was the trickiest as it’s not actually soldered to the board, just ”
strapped” with some wire in three places. One end of the tube is the positive (+) side and the entire center of the tube is negative (-).

I turned it on but couldn’t think of anything to test it with. It would occationally click every now and then but that’s normal background radiation. Then I remembered I had this bowl in the cupboard. I knew the the old 1930’s Fiestaware red/orange color was radioactive because they used uranium oxides in the glaze. This bowl isn’t Fiestaware but it’s probably just as old.

I won’t be eating from it again.