This paper presents a proof of concept of a playful learning device aimed at the enhancement of geometry knowledge acquisition for young children. A novel form of interaction through hand movement has been employed using a theremin-based device. Following a low-cost and energy efficient approach, the presented prototype consists of a digital CMOS ICs, 8×8 LED matrix and Arduino platform. Motivated by the possible IoT utilization in an educational context, a use case scenario has been presented demonstrating potential advantages for the improvement of users’ learning abilities and fine motor skills. This device could provide innovative ways for children to play and learn, fostering imagination while engaging them in STEM-related activities.