In this blog post, I used Screen-o-Matic to provide a short tutorial on the SUM functional in excel. In this video, I also showed viewers how they can use contrasting colors and font sizes to apply the signaling principle (Mayer, 2014).

Reference:

Mayer, R. E. (Ed.). (2014). The Cambridge Handbook of Multimedia
Learning (2nd ed.). Cambridge University Press. https://doi.org/10.1017/CBO9781139547369