TeachBack

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Pre-made lessons (good for quick trying out)
Add your own notes (Can see youtube video for more depth or try it yourself with "Try it out" links.)
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Inspiration

Sometimes I read something and think I understand it, but when I try to explain it, I get stuck. That was the idea behind TeachBack. I wanted to make a tool that helps people notice what they’re missing and practice explaining it again.

What it does

TeachBack lets users choose a topic, read a short reference, and explain it in their own words. It checks for important concepts and some common mistakes, then gives them a question to think about before trying again. The current version has three topics: photosynthesis, compound interest, and binary search. Users can compare their attempts and download their practice notes.

How we built it

The app uses HTML, CSS, and JavaScript. Its feedback comes from rules written for each lesson. It doesn’t use an AI model to judge answers. Practice history stays in the user’s browser. The lessons link to references from OpenStax, Investor.gov, and NIST. OpenAI Codex helped with coding, and the app is hosted through Sites.

Challenges we ran into

One challenge was handling sentences that contain a keyword but say something incorrect. For example, “plants do not use sunlight” shouldn’t count as understanding sunlight’s role in photosynthesis. Another challenge was making the feedback useful. A number alone doesn’t tell someone what to fix, so the app also shows missing ideas, quotes parts of the explanation, and asks a follow-up question.

Accomplishments that we're proud of

We’re proud that TeachBack gives people a complete way to practice: explain a concept, review feedback, and try again. It highlights specific gaps instead of just showing a score, and users can compare their attempts to see what changed. We also built a version that works on both computers and phones, saves practice history locally, and runs without a paid API. All ten automated tests pass.

What we learned

One thing this project showed me is that mentioning the right words doesn’t always mean someone understands a topic. An answer can include “sunlight” and “oxygen” while still getting photosynthesis wrong. That’s why TeachBack shows which concepts it detected instead of giving a grade or claiming that someone has mastered the lesson.

What's next for TeachBack

I’d like to add more topics and improve how the app handles different ways of explaining the same idea. I also want people to test it and tell me where the feedback helps or gets something wrong.