If a student has an academic hobby - writing short stories/poetry in free time, studying the works of an author, collecting and photographing microbe samples - all of which are academic-related and show interest in a field, but which are hobbies nonetheless, can this be mentioned in college apps? For example, if a student has written an amateur collection of short stories over the period of a couple years, can this be used to prove how passionate they are about English? or is it a worthless activity because it may be hard to provide evidence that the student has actually dedicated time and effort to the hobby?
If she doesn’t have them published I feel like it would be difficult to prove the amount of time or effort and skill that goes into her stories and poems. Does her school or town have a literary magazine? Perhaps she could have them published in a local newspaper? Regardless, this is not a “useless hobby” just because it’s difficult to prove to colleges! If she enjoys it, then it’s not useless 
Colleges rarely ask for proof of extracurricular activities, unless they’re truly distinct ECs like winning national mathematics competitions, raising large amounts of money for charities (like six figures), prestigious internships, publication in academic journals, etc. For smaller, more personal hobbies such as you’ve mentioned, they aren’t going to ask for verification. They are certainly relevant and academic hobbies though, and should definitely be mentioned.
@Qwerty568 That was just an example, actually, not based on a real person, but I’m asking because I know quite a few people who have so much passion for their hobbies that when they are asked “so what clubs are you in?” they can only list a couple mediocre clubs, and have no way of saying “but I’m an avid painter/I collect samples from the nearby pond and study them/I have a collection of 100 poems sitting on my desktop right now”…of course they love what they do, but it just seems like a shame when they can’t list these things as a true extracurricular and demonstrate to colleges how passionate they are about their interests.
@comfortablycurt
Refreshed & saw your response, I hope you’re right! I definitely agree they should be mentioned, and hopefully colleges take them seriously, because sometimes I worry that students who are official members of “book club” - a club which, at my school, does absolutely nothing - seem more credible/passionate than students who actually have a deep interest in literature and have made a personal hobby out of it, instead of joining a school club.
Good Question.
I feel that the person should somehow get the hobby recognized. For example, if it is literature, get it published in some newspaper or magazine or create a blog (it’s not that difficult, if you have the resolve!). If he/she is a painter, get some displayed in a gallery. If he/she is a photographer, start an FB page/Instagram Page etc and mention it only if it gets famous.
You see, there are a lot of opportunities to showcase your work. Internet itself has countless. That’s why if anyone is still sitting stuck up with 100 poems on their desktop, they are definitely a fool. Getting them published will help them get constructive critique and develop the hobby into a skill or talent.
Successful students are the ones who are not only good at something, but also know how to get it recognized. If you keep your talent hidden, it’ll always remain hidden.