How to Write a Good Cover Letter

Most students look at a cover letter and see a hoop to jump through. Figuring out how to write a cover letter, for high school students, feels like a formality, something you toss together because the application portal won't let you hit "submit" without it. 

But if you treat it like a checkbox, you’re wasting the most valuable real estate in your application.

Rather than thinking of it as just more busywork, think of it as the “what” behind your “why.” Listing the classes you took, the clubs you joined, and the grades you earned, your cover letter is the connective tissue that explains why a student who loves biology also presents a summer learning high school sports marketing, or why a coder decided to volunteer at a food bank. 

Despite the importance of the cover letter, writing about yourself is admittedly hard. Your parents probably taught you not to brag, so it feels awkward, and it’s even harder to sound professional without sounding like a robot. You might stare at a blinking cursor, wondering how to translate your unique personality into a few paragraphs that an admissions officer or hiring manager will actually want to read. 

That discomfort is normal. But once you shift your perspective from "I need to impress them" to "I need to tell them my story," the words start to flow a lot easier. If you’re curious about how to write a good cover letter (ideally, without tearing your hair out), this guide is for you. 

Why Cover Letters Still Matter

You might hear people say cover letters are dead, but don’t listen to them. In a stack of identical resumes, where every applicant has a 4.0 GPA and is president of three clubs, the cover letter is often the tiebreaker.

A resume is rigid, all bullet points and concrete dates. There’s no room for nuance here; a resume can’t explain that you started a coding club because you noticed a lack of resources in your community, or that your interest in high school sports analytics stems from a love of statistics and basketball.

The cover letter provides context, allowing you to connect the dots for the reader. Maybe your grades dipped sophomore year because you were caring for a sick relative. Maybe you don’t have traditional work experience, but you spent three years mastering Python on your own. Your cover letter is your chance to frame those experiences on your own terms.

It also showcases your personality. Admissions officers and internship coordinators are hiring a person, not a piece of paper, meaning they want to know if you’re curious, if you’re funny, if you’re thoughtful. A well-written letter gives them a glimpse of who you’d be in a classroom or an office, turning you from "Applicant #452" into a real human being they want to meet for themselves.

What Makes a Cover Letter Effective

Like any quality piece of writing, the best cover letters have a clear thesis. Instead of rambling about your life story, they make an argument for why you’re the right fit for this specific opportunity.

To start, begin with a hook that’s something besides, “I’m writing to apply for…” The reader knows what you’re applying for. You don’t need to spell it out for them.

Instead, start with a moment. “The first time I took apart a toaster, I couldn’t put it back together. But that pile of screws on the kitchen floor sparked a curiosity about mechanics that led me to…” Immediately, you’re interested. Now, you’re the toaster kid. You have a story to tell and a real connection to the role you’re applying for. You’re a real person, not just an application.

To make this strategy work, you need to be specific. Avoid vague claims like “I’m a hard worker,” because they’re subjective and they mean nothing. Anyone can say that. You need to be the one to prove it. Describe the time you stayed late to reorganize the school library, or the weekend you spent debugging a code as a problem solving activity for fellow high school students. Show, don’t tell.

Your voice should sound like you, albeit a slightly more polished version. If you’re naturally funny, it’s perfectly fine (great, even!) for the cover letter to have a little wit. If you’re serious and analytical, let that shine through. The goal here is authenticity; if you try to sound like a 40-year-old corporate executive, you’ll sound stiff and artificial. 

Don’t forget that structure matters, too. Avoid writing a large wall of text and stick to short paragraphs instead. Make it easy on the eyes. The reader is likely skimming the document, so make sure your main points pop.

Common Mistakes Students Make

One of the biggest traps students fall into is the “resume rewrite.” This is where you take your resume bullet points and turn them into full sentences: “I was the treasurer of the chess club. I managed the budget.” The reader knows this already; they have your resume right there in front of them. You should instead use the cover letter to tell them something new, or to expand on a specific achievement that a generic bullet point simply can’t capture.

Another common mistake is relying on generic templates. These can help you get started if you’re stuck, but admissions officers can smell a copy-paste job from a mile away. If you find a template online that says something along the lines of, “I’m a perfect fit for your esteemed organization because of my dedication and drive,” you need to hit delete, fast. This is fluff (and not very good fluff). It says nothing about you or who you are.

To that point, it’s not uncommon for students to struggle with tone. They might swing too far forward into formal, using words like “herewith,” “aforementioned,” or “utilize,” hoping it makes them sound more sophisticated or more well-educated. But you aren’t writing a legal contract, and simplicity will always win out over jargon. Use normal words, sticking to “use” instead of “utilize” and “mentioned” instead of “aforementioned.”

On the flip side, you also need to be wary of being overly casual. No emojis, no slang, and definitely no text-speak. You want to strike a certain balance: professional, but human.

Finally, watch out for being too self-focused. “Wait, what?” you might be thinking. “Isn’t this letter supposed to be about me?” Yes, it is, but it’s also about what you can do for them. Rather than just listing what you want to gain from an experience, clearly explain what you bring to the table. Sell yourself. 

How Students Can Build Strong Content

Writer’s block is a common conundrum for students learning how to write a good cover letter, but it’s fairly easy to predict: it typically happens when you don’t have enough raw material to work with.

So before you sit down to write a single sentence, do some digging. Look back at your last few years. What are the moments that stand out?

Maybe you struggled with a difficult concept in chemistry, but found a new study technique that helped you ace that final exam. This experience shows resilience and adaptability. Or perhaps you organized a fundraiser that fell apart logically at the last minute, and you had to scramble to save it. That demonstrates crisis management and leadership.

Look at your list of activities, and think about the “why” behind them. You played soccer for four years. Great! Why? Was it the team dynamic? The strategy? The physical challenge? Dissecting your motivations in your cover letter reveals your values, and that’s really what hiring managers and admissions officers want to see. 

Make sure these connections aren’t too abstract, and connect interests to the opportunity at hand. If you’re applying for a biology internship, talk about the specific research that excites you. If you’re applying to a college known for its engineering program, talk about a project you built in your garage. 

This is also an excellent opportunity for you to highlight your growth. There’s no question about it: admissions officers love a growth arc. They want to see that you’re capable of reflecting, learning, and evolving. Discussing how to develop critical thinking skills is one thing; go one step further and show how you applied those skills to a real-world problem. That’s so much more powerful. 

Using Projects to Strengthen Cover Letters

A well-written cover letter, on its own, is powerful. But a cover letter anchored by a specific project is showstopping. A project gives you something concrete to talk about, moving away from abstract adjectives and into the realm of actual evidence.

For example, instead of saying "I’m interested in history," you could describe a research paper you wrote on local historical archives. You can talk about the hours you spent digging through microfiche, the interviews you conducted with local elders, and the synthesis of information you created.

If you’ve done a passion project, like building an app or starting a small business, feature it prominently. Talk about the obstacles you faced: did the code break? Did the product fail? How did you fix it when it did? These stories all work together to form the larger picture of your problem-solving abilities in real-time.

When you mention specific critical thinking examples for students that you’ve engaged with, you add weight to your claims, showing that you’re not just a passive learner, but a doer.

And if you haven’t done a big project yet, that’s okay! You can even frame school assignments or hobbies in a similar way. The key is to focus on the process, the outcome, and what you learned from the experience. Did you organize a family reunion? That’s event planning. You taught your little brother to read? That’s education, and shows off your patience. 

Finally, make sure you highlight your soft skills. Hard skills (like coding or speaking Spanish) are easy to list on a resume. Soft skills (like communication, teamwork, critical thinking, and empathy) are harder to prove, but often more important. The cover letter is where soft skills live.

Customize Your Cover Letter for Different Audiences

You can’t send the same letter to every school or company; a cover letter for an art school will need to be quite different from a cover letter for an engineering program. For academic applications, you'll want to focus on your intellectual curiosity and your research skills. 

For internships or jobs, shift the focus to skills and reliability, as an employer wants to know that you can show up on time, take direction, and contribute to the team. Highlight experiences where you had to be responsible, collaborate with others, or solve practical problems.

As an example, if you’re applying for summer programs for high school students, look at the program’s specific mission. Do they value leadership? Creativity? Community service? Tailor your anecdotes to match their values.

Ultimately, writing a good cover letter doesn’t require you to work magic. You just need to be able to tell a story. More specifically, your story, told with intention and clarity. Your cover letter connects the dots between who you were, who you are, and who you want to become.

So, don’t let the pressure paralyze you. Start with a messy draft. Write like you’re talking to a  friend. Get the anecdotes down on paper, and you can polish the grammar later. The most important thing is the substance: the examples, the passion, the why.

Polygence projects, whether through Pods, our Work Lab, or our classic research mentorship program, are all incredible fuel for these letters because they are, by definition, self-driven and rigorous. Whether you researched admissions results on your own or built a robot with a mentor, that experience proves you have the drive to turn curiosity into action.

So take a deep breath. Open that blank document. Trust your voice, be specific, and hit submit. You’ve got this.