Speaking the Unspeakable: How the Kalimani App is Giving Voice to Tanzania’s Deaf Learners

In a sunlit classroom at Msasani A Primary School, eight-year-old Neema smiles shyly as she watches a cartoon character on a tablet mimic Tanzanian Sign Language. Her fingers flutter as she imitates the signs. For the first time in her schooling experience, the words on the screen are speaking her language. This is the Kalimani App – and for Neema, it is more than an app. It is an invitation into the world of words.

Across Tanzania, thousands of deaf and hard-of-hearing children are struggling with silent barriers that are rarely acknowledged. In most mainstream classrooms, teachers are untrained to support deaf and hard-of-hearing students. Teaching materials rarely reflect deaf learners’ experiences, and digital tools — while increasingly expanding across the continent — often leave behind those who cannot hear and those who sign.

This is the gap the Kalimani App was designed to address. At its core, it is an AI-powered tool that translates text and speech into Tanzanian Sign Language (TSL), making curriculum content accessible to deaf learners. But at a deeper level, it is a technology of belonging — an effort to ensure that every child, regardless of ability, can learn in a language they understand.

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The Problem We Could Not Ignore

Tanzania is home to over a million people with hearing impairments, and an estimated 15,000 school-aged children who rely on TSL. Yet, for many, access to quality education remains elusive. Only a small percentage of teachers are trained in TSL. Textbooks and digital platforms are rarely adapted for deaf learners. In inclusive classrooms, deaf students are often left at the margins — physically present but educationally excluded.

In rural areas, where access to interpreters is even scarcer, deaf students are often completely disconnected from learning. As technology platforms surged in response to the COVID-19 pandemic, it became painfully clear that the digital divide was not just about internet access: it was also about language and accessibility.

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Building Kalimani: A Tool Rooted in Community

At Jenga Hub, a Tanzania-based non-profit dedicated to reimagining education through technology, we asked ourselves a bold question:

What if we could build an app that interprets the classroom, in real time, for deaf and hard-of-hearing learners?

The result was Kalimani, named after the Swahili word for “interpreter.” Developed in partnership with special needs educators, parents, members of the Tanzanian Deaf Association (CHAVITA), and AI developers, Kalimani is the first app of its kind built specifically for Tanzanian classrooms and in Tanzanian Sign Language.

It combines speech-to-text capabilities with TSL avatars, allowing users to see and learn sign language while also engaging with grade-level content. The app currently supports early literacy and numeracy modules, and has now expanded into science, life skills, and digital safety, among others.

Crucially, Kalimani is designed to work offline, recognising the connectivity limitations of many rural schools. Through its AI engine, it continues to “learn”, improving its accuracy with every sign, every correction, every student.

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Centring the Learners Who Are Often Left Out

What makes Kalimani different is not just the technology, but the process. We did not start by coding. We started by listening.

We listened to deaf students who told us how isolating school felt. To teachers who admitted they had never had access to TSL training. To parents who were eager to support their children’s learning but did not know how.

From these conversations, we did not just build an app — we built a shared vision of inclusive learning. We engaged deaf educators to validate signs, test translations, and provide real-world feedback. We piloted Kalimani in schools across Moshi, Shinyanga, and Dar es Salaam, hosting user-testing focus groups and workshops with teachers and learners.

One of our proudest moments was watching a hearing teacher use Kalimani to learn basic TSL greetings, opening up a new line of communication with her student. “For the first time,” she said, “I felt like I could speak to her, not just at her.”

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Beyond the App: Why Inclusive AI Matters

Kalimani is more than a single solution. It is part of a broader belief: that AI should not only be innovative, it must also be just.

In the rush to scale EdTech, we have too often prioritised speed and scale over inclusion. But Africa cannot afford to leave anyone behind — not girls, not children with disabilities, and not learners in rural communities. If AI is to shape the future of learning, it must reflect our languages, our realities, and our values.

The Kalimani App is a small but significant step in that direction. It shows that when we build with, not just for, marginalised communities, we create tools that work better for everyone.

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What’s Next for Kalimani?

The road ahead is ambitious.

We aim to launch Kalimani on both the Apple App Store and Google Play Store by the end of 2025. We are also in final discussions with Tanzania’s Ministry of Education, the Tanzania Institute of Education (TIE), and regional education offices to integrate Kalimani into public school classrooms and teacher training programmes.

In the coming months, we will expand into Kenyan and Ugandan Sign Language, enhance the app’s functionality to include interactive quizzes, sign-to-text features, and additional modules aligned with the national curriculum. We are also exploring zero-rated partnerships with telecom companies to make Kalimani accessible to download without data charges.

At the heart of these efforts is a single goal: to ensure that deaf and hard-of-hearing children in Tanzania — and eventually across Africa — are included in the digital revolution and empowered by it.

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In Conclusion

Technology alone does not transform education. People do. But when the right people — educators, engineers, parents, policymakers and more — come together with purpose, tools like Kalimani become more than code. They become bridges.

Bridges between hearing and deaf, between text and gesture, and between exclusion and possibility.

At Jenga Hub, we believe every child deserves to learn in a language they understand. Every voice deserves to be heard — including those spoken with the hands.

Through Kalimani, we are proving that when AI is built with love, it can speak even the unspeakable.

Written by Nanci Sumari, founder of the Jenga Hub.