Percival Barretto-Ko, who joined Branson in 2023 as a science teacher, has quickly become beloved both for his love of Biology as well as other classes like E-Lab, which focused on entrepreneurship skills. Notably, he won The Mount Tamalpais School Cup in 2025, and was selected to be the Class of 2026’s Convocation speaker. Recently, word spread that his relationship to the school is changing, and I had the opportunity to speak with him to clear everything up.

First, there’s been some confusion among students, so I want to clarify this: What is your plan for next semester, and will you be returning to Branson next year?

My plan is that I won’t be here in this spring of 2026, but I will be back hopefully for next year.

What do you mean, “hopefully”?

Right now, I’m still trying to figure out my schedule, but my plan is, at the very least, to be here for at least one semester next year. Hopefully yearlong, but I’m still trying to figure out my schedule. But my plan is to be back.

What’s motivating this move?

So, long story short, my partner got a job in the U.K., and, for the longest time, it’s always me that dictated the job and they followed along. And so now it’s a good opportunity for me to do the same. 
So, we’re essentially relocating. However, the good news is that we can be flexible. Hence, the plan is to still be part of Branson, at the very least, a semester per year, which is what I’m doing this year. 
But hopefully, in the future, it will go back to full-time.

So this is more of a short-term arrangement than a long-term one?

Yes, that’s the plan.
 It’s more of a short-term change, if you will. Temporary. And then hopefully it’ll go back to part-time or full-time.

How have your colleagues and the school as a whole responded to this?

I mean, everyone’s been supportive. Everyone’s been so supportive. I think it’s more of the usual question of parents, students, and faculty, like, “explain to me again what’s happening next year?” 
But in the spirit of being very supportive and, you know, “I hope that this doesn’t mean you’re leaving.” And I always reassure them, “No, it’s not.” It’s really more just having a slight temporary thing for next semester, and then, again, the plan long-term is to come back.

Do you have any plans yet for your time in London, professionally or personally, that you’re excited about?

The big thing for me is I can never be not busy. 
So my plan is to definitely do a lot of volunteering in a variety of different ways. And my plan is also to be a supportive partner, but also, you know, find ways to be closer to my family as well and see them. And so it’s going to be different, and it’s going to be busy. It’s just that I won’t be grading tests and labs.

What do you think you’ll miss most about being on campus next semester?

I think the one thing that I’ll miss is that sense of community, of always coming back to something that is structured and regular, but also comforting, right? So it’s an interesting balance. So knowing that you’re here at 8:45 and you have the community all the way from the beginning to lunch, et cetera. So I think I’ll definitely miss that.

I think one of the things that I’m missing this year, frankly—just because the last two years I’ve taught Bio—is I feel like I need to get to know the junior class more. I know the senior class, right? But the junior class, just because I don’t teach Bio, I don’t have that this year. And so that’s the other thing that I’m missing out on. But it’s also nice to see the seniors just mature tremendously this year, and then to see them off as well. 

How do you think that living abroad might influence your teaching when you return? Is there anything you’re going to try to study or experience in London that might inform your classes?

I lived in London for about 10 years before coming back to the States, so it’s a second home to me. I always encourage anyone to travel because travel helps, in many ways, to just broaden your horizon. This is going to be the first time ever, since I was in college, that I haven’t had a job for several months. And so it’s going to be an interesting self-reflection as well of “who am I without the structure and how do I react to it?” as well. 
Will I be like, “Hey, this is great! Wonderful!”?—which I doubt. So it will be a good test for me as well. And I hope to bring that back to Branson in terms of just getting to know myself more and being able to show more of myself to the community.

What is it about teaching at Branson and being a part of the Branson community that makes you want to keep this connection when you’re moving across the world?

You’re absolutely right. Honestly, I could’ve just said, “No,” you know, “I’m taking the year off,” and then, you know, I might teach somewhere else and et cetera. But it really is true. I mean, it’s a special community. I don’t have to say it, but the staffulty is terrific, the administration is terrific, from Chris [Mazzola], to Jeff [Symonds], everyone’s been very supportive. But I think the one thing I’ll definitely miss is the relationship with the students, more so in terms of seeing their growth, right?… It’s those things that actually matter.

Branson students, myself included, have learned so much from you both in and outside of the classroom. Are there any lessons you’ve learned from us that stand out?

Oh my God, yeah. Students are very good at humbling you—that you don’t know everything. I think that’s the first one. And that you need to keep an open mind.

I think, secondly, when I see the relationships that you have built with each other over four years, it’s nice to see that as well. And it’s nice to learn from that. You have built really strong friendships in the last four years.

And I think the last thing is that students are very good at reminding me what’s important. Because, many times, you can be so focused on your career, and then you realize, “Oh, actually, there are more important things in life.” In the grand scheme of things, it all works out. It’s the same for the colleges, right? I mean, I know the seniors are stressed about where and when they’re going to get into their dream college, and then you realize at Graduation that everyone’s happy. Everyone got into the college that actually was right for them. And so that’s also a reminder for me.