“Learning Curve” is episode five of season three of Stargate SG-1.
Daniel is examining the stargate installation on a planet inhabited by some potential allies, who seemed to be related to the Aztecs (although with rather less bloodshed), with advanced technology.
The people of the planet are doing an exchange of knowledge, which includes leaving a naqadah reactor (the first time one of these has come up I think; they are prevalent in later shows) on Earth for several weeks. A young girl remains behind on Earth to help Sam understand how the reactor works, whilst Teal’c and Daniel remain on the planet.
The culture’s children seem a bit odd – extremely intelligent and knowledgeable. Which is because they are infested by nannites. The team discovers some rather disturbing knowledge regarding the children.
An episode which has been influenced by the techno-fear of nanotechnology (a technology that has probably come a lot closer to fruition since this episode was first aired).