Does he need another EC if he is absorbed in sports?
I would make sure he has some healthy down time.
You don’t mention what college targets. Unless he’s recruitable, the top schools expect the right in and out of hs activities beyond the one sport. If he’s a stem wannabe, don’t leave adcoms wondering why no math/sci ECs, robotics experiences (especially the collaborative work.) Same if he’s humanities, in regard to debate, etc.
I suspect you and he don’t yet realize how top holistic colleges will look for more than one activity that interests him. In fact, being open to other ECs, volunteer, and more, is a plus for colleges interested in how applicants do engage.
I would not add an EC just to get into college. Let him evolve naturally. He’s young.
Part time job ?
Investing/stock trading via computer.
Hot air ballooning.
Skydiving ? (Very relaxing & a lot easier than one might think.)
I think he really needs some sort of volunteer work. Everyone has time to volunteer, even if it’s just one hour per week.
One reason he may not be showing interest in other activities is because he truly has no idea what his other interests are or what else he’s good at. That’s the problem with playing a sport from a young age and at a high level.
This is the perfect time to expand his horizons!
Volunteering would be a solid choice for this kid, even if is just once in a while, but consistent. There are many schools that actually care about volunteering, and you can search the common data set for each school to see if it matters. If there is a check mark in the box showing that the school considers it, and the kid doesn’t have any, that’s a strike point.
There may be ECs that come up naturally as the years go by. NHS, Best Buddies (a lot of athletes did this at D’s school), being on a prom or homecoming committee, student government, joining the theater group because a friend did. What he should do is keep a record of all the little volunteer jobs he does, any clubs he joins (and maybe who the adviser was), so he can remember when it comes time to fill out the apps.
^ That’s great advice about keeping track of everything.
My student made a spreadsheet (one for each year) that had the date, time, number of hours, organization name, duties, location, supervisor name and contact, etc., for all volunteer hours.
As an example with my kid, one of the 10 activities he listed on his common app was Volunteering. He then listed many of the clubs, groups that he worked with to gain volunteer hours during high school.
Our town has a "challenger league’…it is sports for disabled kids. Volunteers help them one on one in the sport.
Refereeing is a nother great idea
You are all dead on! Yes, he is aiming for a top college, and he seems to feel that his tennis will take care of it. I have told him otherwise, and he should know already from his older sister’s experience - in a top college, with a non-recruitable sport, so she had other strong ECs. So frustrating as a parent that he’s not listening! He’s aware that he’s marginally recruitable (perhaps a couple of the Ivies - I’ve seen them take as low as 3-star players before), and who knows what will happen the next 3 years, with injuries, etc. He will definitely be volunteering, as his school has a requirement, and we believe in doing that. It’s the other strong EC that I’m concerned about. He was extremely excited about the fantasy football league, but when I mentioned the stats and the big-data (I hear it’s a hot topic these days!) part of it, his response was “but that’s already all on ESPN. How would I add to it?” I will have to brainstorm with him further on that aspect.
Becoming a ref is a fantastic idea, and I’m already looking into wheelchair tennis leagues - I wonder if they’d consider having him as an assistant coach. The “clean athletes” idea is also great - they came home the first week with myriad stories of athletes (not just students) who vape openly. They don’t have a FBLA club at his school, so that might be an option, to start one. He has shown interest in the stock market in the past, but his dad and I are definitely not ‘business’ types, and are clueless with regards to this.
Thanks again for the support! I think sometimes with the student-athletes, there’s an innate self-confidence which precludes listening to parents, even with non-sports topics. 
Top tier schools will look for a well rounded student. One who has leadership roles, community and school involvement. I would branch away from athletics. What type of major is he looking towards?
He just started ninth grade - while it’s good that he’s thinking about it early, I’m with compmom. I don’t think he needs to stress about it. It’s the beginning of the year - he can develop some interests naturally, and think about things to get involved with next semester or next year.
If he’s interested in sports analytics, I bet that there’s someone at his school or district level that tracks stats for the high schools in his district/area. Maybe he could talk to his coach to figure out who to talk to about that. Baseball is the sport that started this all (Nate Silver, probably the most well-known statistician of our time, started out as a sabermetrician - someone who does baseball stats), but other sports are starting to get into it now, too. (Don’t worry about the big data part yet. That requires some advanced computer science skills, too. His goal should be getting his feet wet and seeing if he likes it.)
I wonder if there’s a physical therapy clinic or office nearby where he could volunteer or intern, particularly a physical therapist who works with athletes or uses sports in their rehabilitation program. A rehabilitation clinic is another suggestion.
Sports analytics won’t tip him in. It may be solitary or mostly so. There’s a measure of good old humility needed: that you’re not too good for work with peers. And savvy: that top colleges freaking want kids who interact, team up, try new things, can expand and stretch. Not just baby steps, either, that random hour helping someone. Or some other twist on his real one activity, tennis.
OP is asking, imo, for help with directions. I think she rightly gets that some lone pursuit or two isn’t it. Nor is indulging the attitude, if anyone thinks he’ll want a top college. He needs to get out of his narrow thinking. Grow, gain some perspective. Wind it up.
Yes, he can experiment in 9th. But try something. Adcoms will look at commitments over time.
Not many shortcuts, lol. Get him into some good comm service now, rolling up his sleeves and working directly with the needy. A soup kitchen is an idea. Not a coat drive once/year or shelving library books. Or some do-little club a 14 year old “founds.” It doesn’t have to be hours/week. Even one afternoon per month, regularly, can add to 3 years by the time his apps are due.
The competition will have good service, clubs, sports and more.
I don’t intend to demean community service, but unless it’s something special it’s not likely to be a decisive factor for admission to a highly selective college. I’ll reiterate my earlier idea about fantasy sports. It’s a competitive GAME, sure. But it’s truly about statistics and possibly coding. And it could involve teamwork, students working in 2’s or 3’s, competing against other small groups, in using tools of statistical analysis, modeling individual and team performance. However, if this isn’t interesting – or he thinks ESPN has all the stats already (they don’t; they’re constantly adding to or improving them) – then I’d still recommend that the OP’s son do something creative or requiring special tools, not just “hours” of community or volunteer work. (One of the challenges in more advanced sabermetrics is accounting for the contributions of players in the more fluid sport like soccer, hockey, or basketball – as opposed to more “positional” sports like baseball and football.)
Gaming or fantasy leagues aren’t one of the qualities top college look for. In contrast, compassion and willingness to get out of your own little comfort zone are. And comm sevrice can be initially pushed as a family (or religious) value, even done as a family until he gets used to it.
It doesn’t have to be special, like singlehandedly saving thousands of lives or running off to vaccinate scores of kids (or any of the pay-to-go pograms. I do see developing an art skill as important to art colleges, sure.) But the c svc should be more than just showing up and putting in a few hours. A lot of high school service is just that: get there, take off your coat, hang with your buds, and it’s practically time to leave. The reason I often suggest a meal site is it requires work, they nearly always need help, and you face the needy in reality, not some distant concept. I’d guess working with the disabled on a regular basis can teach the same.
And I think all of us who suggest vol work are saying as a start. Yes, to robotics or math team, etc, if he wants stem. The top colleges will look for this collaboration, this experience, for stem. But they also want breadth, not just depth and not just unilateral.
I think CC sometimes gets confused between what you do because you like it and what you do for growth and to do some good around you.
So even if he loves analytics or whatever, he still needs to round himself- and show the willingness to do so.
On a side note, other than athletic recruits, I’ve seen Olympic track athletes get sidelined for not being rounded, seeming not to give a hoot for anything but their sport.
I’m not pushing fantasy sports per se. The only reason I’ve mentioned it at all is because the OP’s son has an interest in sports, and perhaps doing an EC related to it (aside from playing the sport). Creating something of wider interest or applicability is a challenge in any area of endeavor. I’ve been fortunate that my career demands that I create things. 99% of the people of the world will never see or be interested in my “creations” (mainly research publications) but within my specialty I know that tens of thousands of people have read my work and many have built on it.
My community service idea had less to do with admissions and more about getting the OP’s son out of his sports’ bubble; your idea keeps him in the bubble.
The son needs to broaden his worldview. He needs varied life experiences. He needs to work with people from different backgrounds. He needs to develop leadership and other skills that will benefit him in college and beyond. All of this and more can come through volunteering.
As @lookingforward said, this is just one component in creating a well-rounded human being, but I think it’s an important one.
Ivy League does not recruit 3 stars. You need to look at the ranking around Junior year to understand the ranking that was used for recruiting, not the final ranking or stars. All other 2-3 stars that you see there are walk-ons who got in on their own merit and through various non-athletic hooks.
My recruited athlete was only allowed to do school, her sport and volunteering. No school clubs.
My two sons played a competive sport. Not at a high level beyond regional play, but time consuming.
They both volunteered at a senior center helping senior citizens with personal technology devices. This was an established program where they could help at drop-in sessions working one-on-one with seniors. Potentially could be organized at a senior center if it doesn’t exist.
They helped dozens of seniors over the years navigate social media to connect with family, reset passwords, search for information, etc.