The textbooks I used to teach already flawless and naturally incorporate Biblical principle through out my lessons. I always expand on these and make sure they aren’t just read through and overlooked though. I try to incorporate a lot of Biblical discussion when teaching. For example, when teaching about the colonization of the colonies or the Revolutionary war I will ask questions like “How should a Christian respond to that”, “Do you think those decisions pleased God”, “Does God support us going to war and would He take a side?”. It just is a very easy way to make sure we take whatever we’re learning and make sure we’re growing our faith and Biblical worldview through it.