Posters, acknowledgement slides for talks, and most importantly, acknowledgement sections in papers should contain the (A) NSF acknowledgement and (B) NSF disclaimer below. Here are versions you could use. The minimalist should almost always suffice. Note that the disclaimer never needs to be modified; you should include it verbatim.
Minimalist version
Acknowledgement: “This material is based upon work supported by the National Science Foundation under Grant DGE-1747486.”
Disclaimer: “Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.”
Elaborated acknowledgement that promotes SLAC
Acknowledgement: “This material is based upon work supported by the program in Science of Learning & Art of Communication at the University of Connecticut, which is supported by the National Science Foundation under Grant DGE-1747486.”
Partial support acknowledgement
The minimalist acknowledgment is appropriate for any degree of support. If you wish to be more precise, go ahead, e.g.: “This material is based upon work supported in part by the National Science Foundation under Grant DGE-1747486.”
Does a conference or publication require the PI to be specified?
Occasionally, guidelines for a conference or publication may specify that you list the PI. If so, just add “(J. Magnuson, PI)”.