Here's an electronics project that may not have a huge amount of practical applications but definitely has a wow factor for educational use.
Electronics hobbyist weblog Whiskey Tango Hotel used stepper motors from a dot matrix printer to control the knobs of an Etch a Sketch toy. From there a temperature sensor was wired to the project so that temperature changes are recorded in a way where the Etch a Sketch acts as a strip chart.
Once the stepper motors were properly identified the author used three microcontrollers to drive the motors and created a mount for the Etch a Sketch using a baseball display case. Once the mechanical function was figured out the author wired in a temperature sensor and two buttons to move the stylus on the Etch a Sketch. After all of that was working the software was debugged until it correctly "sketched" the temperature every 750 milliseconds.
A full schematic and build details can be found at the source link below.