What if you could teach kids how to add and subtract, without numbers on a screen and without expecting them to count? That was the motivation behind Kalculator, a fully mechanical toy designed to help kids explore math in a playful way. I led the concept development and design, working closely with a teammate to model and refine the final toy in SolidWorks.
The Design Prompt
Build a toy that displays the correct result for two single-digit inputs (1–9) through physical interaction alone, and excludes arithmetic equations that result in negative numbers.
The Design
Inspired by old-school multiplication tables, I designed a system where children slide along two number lines to select their inputs, say 1 and 5, and the answer pops up automatically on a rotating wheel.
The magic happens through a 9-sided answer wheel that slides along a shaft with a helical groove. Each inch of horizontal movement causes the polygon to rotate by 1/9th of a turn, revealing a new number.
So when the inputs are 1 and 5 (or 5 and 1), you slide the wheel to where 1 and 5 intersect, and the face marked 6 rotates into view.
Addition side
Subtraction side
Reflection
This was one of my favorite projects because it turned a simple math problem into an opportunity to design something clever and fun. Everything was modeled in SolidWorks and built with the mindset that learning should feel like play.
