While my school was fortunate enough to have Spec20's for students to use, since these devices are very expensive, they are not accessible to most schools. SpecDroid uses the android devices camera and works alongside a housing built of legos to replicate the Spec20's function with "good enough for educational use" results. As an added bonus, SpecDroid determines the wavelength of light for the user so that's a step they won't have to go through.
For more info on what a Spec20 is: https://en.wikipedia.org/wiki/Spectronic_20.