Making a copy of anything could be considered copyright infringement, but what if it is for personal use rather than for distribution? Suppose I print out or take a screenshot of a webpage or a lecture presentation or an eBook and store it somewhere? Would this be likely to be fair use? I would guess the answer is no in some cases (you cannot copy an entire eBook intended for temporary use), but yes in most cases, such as if I print out or download a page on a publicly accessible webpage for personal use.
It is not possible to say that this is generally fair use, although sometimes it would be.
A copy for personal use is still a copyright right violation on its face, and fair use does not categorically exclude non-commercial or personal use of copyrighted works. It is a highly fact specific inquiry.
The likelihood of anyone discovering that you have done so and deciding to sue over it is slight, but that doesn't mean that there isn't potential copyright infringement liability.
Compare this to speeding. People do it all the time, and even driving one mile per hour above the speed limit is still a traffic violation. But it is rare for less serious violations to be ticketed.
As a practical matter, if a person prints out a section of work on that person's own local printer, and does not provide this copy to anyone else, there is no plausible way in which the copyright owner would learn of it, and so no action could be taken. If the owner did learn, possible damages would be slight at best, as the person had made no profits, and the owner sustained no losses. Few owners in such a case would actually file a suit.
But leaving that aside, let us consider whether this would be a fair use under US copyright law, that is 17 USC 107.
- Factor (1) the purpose and character of the use: The use does not seem to be commercial, and might be considered as "research". Thus it probably favors fair use, but perhaps only slightly.
- Factor (2) the nature of the copyrighted work: If this is a "lecture", it probably favors fair use a bit, but not enough information is given in the question to really asses this factor.
- Factor (3) the amount and substantiality of the portion used in relation to the copyrighted work as a whole: If the work is an ebook, a screen shot or even a few pages is only a small portion of the whole. If it is a lecture, then it is hard to say how much of the whole this might be, but probably significantly less than all of the work. Again, there is not really enough to analyze, but this factor probably favors fair use to some extent.
- Factor (4) the effect of the use upon the potential market for or value of the copyrighted work: There seems to be no effect whatever, so this factor clearly favors fair use.
In short, such an action might well fall under fair use, depending on details not clearly stated in the question, such as the nature and length of the work, and the amount to be printed out. It is not possible to say with assurance if fair use would apply, without specific details of the work and what part would be printed.
In this comment a user questions just how "fair" fair use is. "Fair use" was initially a judge-created concept, and had a lot to do with what judges considered fair. It has now been codified in 17 USC 107 (borrowing much language from previous case law) but the statute explicitly allows consideration of "other" unspecified factors in addition to the statutory four factors. That is how "transformative" became an important factor. In case law judges often discuss whether a use "serves the basic principles of copyright law". It might be called "socially positive use". But it is not at all a cut&dried factual deterioration. It is always fact-driven, but also always a judgement call.