Written text can decrease learning if concepts last more than 2-3 minutes
Modality and Redundancy Principle
If I use text and visuals and narrate at the same time, you’re not going to learn anything and just get angry and frustrated and stop paying attention because OMG this is so boring. Oh was there a picture over there. Your visual pathway cannot process all of this. And this text is the same info that I narrate so useless anyway.