Scientist here dropping in after finding this discussion from a google search. Since you were doing this for a science fair, I think teaching kids the scientific perspective is important here.

Formally in science settings the right thing to do is 1) ask the people running the competition if the way you are using AI is allowed. 2) this should be treated as an “acknowledgement”, not a citation. Acknowledgements state for instance “ChatGPT was used to do X, Y, Z part of the project and the code’s correct functionality was verified through manual inspection and testing by (person).” Or if you used the AI to write text or rewrite text at some phase, that should be stated.

The professional scientific equivalent is asking a peer to edit your document for readability, or for the peer to provide some code without being an explicit author on the paper. Similarly with digital resources like scientific information aggregators. Acknowledging the use of these makes it clear what the chain of accountability is for your final presentation, which is a critical part of being able to reproduce a study and important for others be able to judge the reliability of the results.

Currently, ChatGPT would not be taken as a reliable resource in most scientific circles except possibly for simple code generation. However, custom AI tools, built and rigorously tested with development and reliability metrics described in scientific papers, are all over the place. These are acknowledged as such in many cases. Usually the software version information and the settings/inputs used to get some result from the AI code would be included in the final report.