Exploring the role of tangible interfaces in education for accessibility

Project Overview

While most of the educational systems for challenged learners have been inspired and adapted from developed regions, a little work has been done in implementing such systems for intellectually and developmentally challenged (IDC) children in developing regions. We conducted a study at a special school in North-eastern region of India to understand the needs and problems of these children and their teachers. Some of the critical findings include the ineffectiveness of the existing teaching methods and the mental exhaustion of teachers while addressing the challenges faced by these children.

This project presents CoinBeam, a tangible interactive system which helps these children to learn the concepts of currency denomination splitting. This project focuses on a specific use case of teaching currency denomination splitting to these students to highlight the collaborative, associative and social aspects of these physical learning systems.

  • CoinBeam was awarded the Best Student Paper Award at the International Conference on Human-Computer Interaction, India HCI 2015.

Team members: Samadrita Das, Dipti Kumari, and Pooja Dhaka

Role: Field Research, User Research, Affinity Mapping, Conceptualization, Prototyping and User Testing

Domain: Tangible User Interfaces

Tools: Fiducial Markers, Reactivision, Arduino, Legos

Duration: 3 months

What is Currency Denomination Splitting?

Breaking higher denominations of currency into smaller ones

Current teaching method

Major pain points of teachers

Presenting CoinBeam

To address the problems faced by the teachers while teaching money matters to students with developmental challenges, we designed a tangible interface system called CoinBeam, an interactive learning system that recognizes and responds to the denomination of  the coin placed in the pan and reaches an equilibrium position only when it is balanced by the cumulative value of the coins in the other pan.

Design Process


To understand the goals and organizational structure of Shishu Sarothi, a premier center for rehabilitation and training for multiple disabilities in Guwahati, Assam (India) and to identify our target group.


At the end of the field study, we understood the organizational structure of Shishu Sarothi and their current pedagogy. Also, we identified our target group for the project.


To understand the goals, needs, requirements and aspirations of students and teachers of our target group.

Focus group study with the director, two psychologists, a physiotherapist and a special education expert

Participatory study with 11 students

Contextual inquiry with 4 teachers


The analysis of the user data gathered helped in building persona to focus on the goals and the frustrations of the target group. This persona formed the basis of the brainstorming session for creative solutions.


The concept of CoinBeam was born out of the analogy of the balance beam. What if instead of weights, coins are used to balance the pans!

Schematic Diagram

Prototyping tools

The fiducial markers are encrypted with the face value of the coin which can be tracked by camera using reactivision software.


To test the prototype on field to obtain feedback from the users and discover the usability issues in the system.


To evaluate the system, the students were given a task of splitting a ten rupee coin into smaller coins. The teachers acted as moderators in this session.


The system was evaluated with four teachers, four students and the director of the organization. The students were silently observed during the task and the teachers and the director were interviewed at the end of the session for their feedback and suggestions.

Formative evaluation at Sishu Sarothi

Insights from user testing

Future Work...

Our initial results from the evaluation were very promising and the system was well accepted by the teachers, therapists and the students. Further, we aim for a large scale deployment and evaluation of the system across more schools and to investigate its effectiveness as a learning tool for more complex financial transactions.