  Smartphones are widely available and used extensively by students worldwide.
These phones often come equipped with high-quality cameras that can be combined
with basic optical elements to build a cost-effective DIY spectrometer. Here,
we discuss a series of demonstrations and pedagogical exercises, accompanied by
our DIY diffractive spectrometer that uses a free web platform for instant
spectral analysis. Specifically, these demonstrations can be used to encourage
hands-on and inquiry-based learning of wave optics, broadband vs discrete light
emission, quantization, Heisenberg's energy-time uncertainty relation, and the
use of spectroscopy in day-to-day life. Hence, these simple tools can be
readily deployed in high school classrooms to communicate the practices of
science.
