The work demonstrated that a low-cost spectrometer and ImageJ serve as an accurate, reliable, and robust model and tool for learners to grasp abstract concepts in the Introductory Physics Lab Course context. The model design was self-paced while promoting active and peer learning for students. Image analysis within the experimental activity adds to the novelty of the lesson. Within the experimental accuracy, the measurement was shown to correctly identify the absorption spectra of Potassium Dichromate, Methylene Blue, and Potassium Permanganate and to describe the subtractive color-mixing model where Cyan absorbs Red accurately, Magenta absorbs Green, and Yellow absorbs Blue.