Why do you teach new players to build armour on Ashe against Nunu?
I've gone through the introduction to League of Legends a couple times, and I think it could help new players understand item builds better if they were not first introduced to poor item builds in the introduction.
If your intro Ashe was allowed to build a BortK or IE to help her attack better, or even a Spirit Visage to make you tankier against Nunu, I think it would help new players understand what is better for an ADC like Ashe.