Optics is probably one on the most exciting topics in physics. However, it also contains some of the
less understood phenomena by students—the light spectra obtained from the diffraction of light. The
experimental study of light spectra for studying radiating bodies, usually requests sophisticated
and expensive equipment that is not normaly affordable for schools, and only a few teachers know how
to measure the wavelength of light in a spectrum. In this work we present a simple and inexpensive
setup, with enough accuracy for measuring light spectra to be used both in physics and chemistry
classes. We show how freeware software Tracker , commonly used for teaching mechanics, can serve to
measure wavelengths with about 2 nm of resolution. Several approaches to the calibration of
different setups are also provided, depending on the degree of accuracy demanded.