Letterling

Handwriting practice that kids actually love.

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Inspiration

1 teacher. 22 kids. 5 minutes each. That's 110 minutes a kindergarten teacher doesn't have. We wanted to create a tool that helps kindergarten teachers overcome the challenge of being everywhere at once — introducing an AI classroom assistant that provides live handwriting feedback. Teachers set up student groups and start a session where students can independently learn to write their names, one letter at a time.

What it does

The only login required is the teacher's. From their dashboard, teachers store student information, track active sessions, and monitor progress. They share a single 4-digit code with students to begin. Students need no login and no typing. A simple number keypad gets them into the session. From there, they independently practice writing their name one letter at a time — guided entirely by on-device whiteboard annotations and immediate text-to-speech feedback. No reading comprehension required. Every iPad (device) becomes a personal assistant. Students are no longer bottlenecked by having just one teacher in the room.

Tech Stack

  • Frontend: Next.js + React, tldraw (whiteboard canvas)
  • Backend: Next.js API Routes, Supabase SDK
  • Database: Postgres (Supabase)
  • AI: Gemini 2.5 Flash Lite (annotation + text feedback), ElevenLabs (TTS), Claude Code/Codex

User Interviews

1. Elementary School Teacher's Assistant

Though not a kindergarten teacher, we wanted to hear from an instructor who works closely with young children. Her biggest challenge was keeping students engaged and on-task for extended periods. To address this for Letterling, we made the session length customizable: teachers control how many letters a student completes before the turn passes. To prevent a student from getting stuck, the turn automatically advances after 5 attempts on a single letter. The text-to-speech voice is also configured as a fun character to hold students' attention.

2. Kindergarten Education Assistant

Our second interviewee struggled with managing multiple students at the same time, a near-universal challenge in early childhood classrooms. Letterling addresses this with an all-in-one teacher dashboard that shows progress across all students from a single screen. Teachers control when to start or pause a session, and have full flexibility over group size and the letter limit per turn.

Outcomes

  1. Increase the teacher to student ratio in classrooms
  2. Reduce the effort required to give live feedback to student handwriting
  3. Improve interactivity while learning with visual & verbal cues
  4. Minimize number of clicks and manual help required by students to learn to write their name

KPIs

  1. 2 or more students actively practicing simultaneously with feedback
  2. Live feedback delivered in < 3 seconds per letter submission for high interactivity
  3. 0 teacher interventions required for a student to complete a full turn (letter prompt → draw → feedback → pass)

Built With

  • claudecode
  • codex
  • elevenlabs
  • gemini
  • next.js
  • react.js
  • supabase
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