Is this the correct abbreviation for instructor (instr)

Yes, with a period after (instr.)

no

Yes, "instr" is a commonly used abbreviation for the word "instructor." However, to ensure accuracy, it is always advisable to refer to a reliable source or style guide, such as the Associated Press (AP) Stylebook or the American Psychological Association (APA) Style Guide. These guides provide standardized abbreviations and can serve as a reference when abbreviating words or titles.