It is not plagiarism if you use "common knowledge."
Common knowledge is any knowledge that a person can reasonably expect others to know. Anything that is common knowledge does not need to be cited.
Examples of common knowledge:
- The date of the signing of the Declaration of Independence
- The composer of a popular song, for instance, that Taylor Swift wrote "Love Story" (but if you use the lyrics, you must cite)
- The knowledge that there are many Spanish speakers in Florida (but not the percentage of Spanish speakers)
It is not plagiarism if you quote yourself or use material you created, so there is no need to cite if you:
- write about your own life
- use your own survey/experiment results
- use your own art work, photographs, video, audio, etc.