Pub 970, chapter 1. https://www.irs.gov/pub/irs-pdf/p970.pdf
A tuition waiver is only a discounted price.
Any scholarship used for qualified expenses (tuition) is tax free.
If you received no document reporting this (1099, 1098-T), you have nothing to be concerned with. Even when a 1098-T is used, the box 1 amount offsets the box 5 amount.