Inside eSpark’s AI Teacher Assistant: RAG, Evals, and Real Classroom Needs

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How do you build an AI-powered assistant that teachers will actually use?
In this episode of Just Now Possible, Teresa Torres talks with Thom van der Doef (Principal Product Designer), Mary Gurley (Director of Learning Design & Product Manager), and Ray Lyons (VP of Product & Engineering) from eSpark. Together, they’ve spent more than a decade building adaptive learning tools for K–5 classrooms—and recently launched an AI-powered Teacher Assistant that helps educators align eSpark’s supplemental lessons with district-mandated core curricula.
We dig into the real story behind this feature:
- How post-COVID shifts in education created new pressures for teachers and administrators
- Why their first instinct—a chatbot interface—failed in testing, and what design finally worked
- The technical challenges of building their first RAG system and learning to wrangle embeddings
- How their background in education shaped a surprisingly rigorous eval process, long before “evals” became a buzzword
- What they’ve learned from thousands of teachers using the product this school year
It’s a detailed look at the messy, iterative process of building AI-powered products in the real world—straight from the team doing the work.
Show Notes
- Guests:
- Thom van der Doef, Principal Product Designer at eSpark
- Mary [last name], Director of Learning Design & Product Manager at eSpark
- Ray Lyons, VP of Product & Engineering at eSpark
- Topics covered:
- The origin story of Teacher Assistant: connecting administrator mandates with teacher needs
- Why the team abandoned a chatbot interface in favor of a more structured workflow
- How retrieval augmented generation (RAG) and embeddings shaped the product architecture
- Lessons learned from debugging semantic search vs. keyword search
- Building evals with rubrics, Braintrust, and a human-in-the-loop approach
- What’s next for Teacher Assistant: more contextual recommendations using student data
- Links & References:
- eSpark Learning
- Braintrust.dev – evals and observability for LLM applications
- AI Evals Maven Course by Hamel Husain and Shreya Shanker
Chapters
02:05 Overview of Epar's Adaptive Learning Program
07:19 Challenges and Insights from COVID-19
17:06 Developing the Teacher Assistant Feature
24:55 User Experience and Interface Evolution
34:29 Chat GPT-5's New Features
35:16 Balancing Engagement and Efficiency
35:40 Seasonal Business and Real Traffic
36:29 Technical Decisions and RAG Implementation
38:28 Challenges with Embeddings and Metadata
41:24 Improving Recommendations and Data Enrichment
55:18 Evaluating the Teaching Assistant
01:05:51 Future Plans and User Feedback
01:07:57 Conclusion and Final Thoughts
Full Transcript
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