There are two basic winding arrangements for the electromagnetic coils in a two phase stepper motor, one being bipolar and the other unipolar. ... The unipolar stepper motor operates with one winding with a center tap per phase. Each section of the winding is switched on for each direction of the magnetic field. Source: CircuitSpecialists

Easy Driver Stepper Motor Driver

The EasyDriver is a simple to use stepper motor driver, compatible with anything that can output a digital 0 to 5V pulse (or 0 to 3.3V pulse if you solder SJ2 closed on the EasyDriver). The EasyDriver requires a 6V to 30V supply to power the motor and can power any voltage of stepper motor. The EasyDriver has an on board voltage regulator for the digital interface that can be set to 5V or 3.3V. Connect a 4-wire stepper motor and a microcontroller and you’ve got precision motor control! EasyDriver drives bi-polar motors, and motors wired as bi-polar. I.e. 4,6, or 8 wire stepper motors.

This EasyDriver V4.5 has been co-designed with Brian Schmalz. It provides much more flexibility and control over your stepper motor, when compared to older versions. The microstep select (MS1 and MS2) pins of the A3967 are broken out allowing adjustments to the microstepping resolution. The sleep and enable pins are also broken out for further control. Source: SparkFun

Depending on the funding available maybe build an X,Y plotter

Have the students figure out how to assemble some "ActoBotics" from;
https://www.servocity.com/actobotics

Mayabe even build an x,y,z Pick and Place machine.