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Caltech  /  Essays  /  Prompt 1

Caltech: STEM experience (choose one)

100 to 200 words

Choose one: (a) Tell us how you initially found your interest and passion for science or for a particular STEM topic, and how you have pursued or developed your interest or passion over the last few years. Or (b) Tell us about a meaningful STEM-related experience from the last few years and share how and why it inspired your curiosity.
What it’s really asking

Either the origin and growth of your STEM interest, or one meaningful STEM experience and why it sparked your curiosity. Both want a specific story with real development, not a statement of passion.

Why they ask it

Caltech wants evidence that your interest is genuine and self-driven. They are testing whether you pursue science on your own time, which predicts how you will thrive there.

Three ways in
The exact spark

Pin the specific moment your interest took hold, then trace what you did because of it.

One experience, deep

If you choose option b, pick a single experience and go all the way into the thinking it triggered.

Show the pursuit

The prompts care about the last few years. Show what you built, read, or tested on your own, not just that you were interested.

✕  Weak opening

“Ever since I was a young child, I have been deeply passionate about science and have always wanted to understand the world.”

✓  Strong opening

“The first thing I ever overclocked was a calculator, and I bricked it, and the bricking is what got me.”

✦ Annotated example · From a leaky tap to fluid dynamics. Written by EssayLens to teach, not a real applicant’s essay. Tap a highlighted line →
It started with a dripping faucet I was told to ignore. Instead, I timed the drips and noticed they sped up when the basin filled. 1That bugged me enough to start a notebook of "things water does that I cannot explain." By tenth grade it held forty-one entries: why honey climbs a spoon, why a stream narrows as it falls, why my tea cooled in a ring. I taught myself the continuity equation to settle the narrowing-stream question, then got humbled when it could not touch the honey one, which needed viscosity. 2So I built a cheap viscometer from a syringe, a kitchen scale, and a phone slow-motion camera, and measured honey, oil, and dish soap against published values. My honey reading was off by twelve percent. 3Chasing that error taught me about temperature dependence, which sent me into a summer of reading about non-Newtonian fluids. 4By spring I was running the syringe rig at three temperatures and plotting the curve, just to watch it bend. I still cannot fully explain the honey. The notebook now has sixty entries, and the unanswered ones are the reason I keep going.
  1. 1Opening with a tiny, concrete, almost-mundane observation signals the genuine curiosity Caltech rewards. The interest begins with noticing, not with an award or a buzzword.
  2. 2Showing a tool that worked AND one that failed demonstrates depth of process. Real inquiry includes the limits of your current understanding, not just clean victories.
  3. 3The homemade rig and the specific error margin prove she actually did the work and checked herself, rather than gesturing at a finished result.
  4. 4The phrase 'chasing that error' makes the through-line explicit: one unanswered question pulls her to the next, which is exactly the multi-year arc the prompt asks for.
Stuck? Start here
  • What is the exact moment your STEM interest took hold?
  • What have you done about it on your own in the last few years?
  • What specific question keeps pulling you back?
Before you submit
  • Is there one specific story, not a general claim?
  • Did you show self-driven pursuit over time?
  • Does your real thinking come through?

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