It's no secret that extracurricular activities play a major role in college admissions. But most parents and students do not understand the proper way to approach them and end up wasting significant effort for things that will not make them stand out compared to thousands of other students.
Participating in dozens of different events and activities, merely to fluff up one's resume, will not accomplish anything. This includes being a member of multiple clubs or participating in random volunteer events. That's not to say there is no value in these things. But in terms of college admissions, their impact is minimal.
To better understand this, put yourself in the shoes of the admission officials of a prestigious school like UCLA, which can get around 140,000 freshman applicants who are competing for a little over 10,000 spots. The overwhelming majority of the applicants fail to impress the admission officials. This is not because they lack extracurricular activities. Most students have a long list of them. But their extracurricular activities just blend in with those of all the other applicants. They all look the same.
There will be thousands of people that went to MUN conferences or participated in debate competitions. There is no shortage of varsity athletes, students who have traveled around the world, photographers, or immigrants that had to learn English to catch up with their classmates. These activities can serve as foundations to build a more sophisticated theme about yourself. But by themselves, they are not impressive, and unlikely to get you into the most competitive schools.
An easy test to determine how much a particular activity will impress universities is to examine its barriers to entry. How difficult is it participate or achieve? For example, summer programs that anyone can sign up for (if they pay enough money) have zero barriers to entry. Merely participating in one will not help you get into a top tier school. Similarly, something like a video production class which only needs you to sign up, will not make you stand out.
So what things do stand out?
Activities which are competitive or rare. A summer research program that only accepts a small percentage of the applicants is likely a far better use of your time. Or submitting a short film to a high school student film festival is out of the ordinary. The best activities take years to accomplish and may not have a clear, conventional path laid out to reach.