Which Principles of Material Design are most important for you? Why?

Which Principles of Material Design are most important for you? Why?

I teach mostly children and teenagers and from experience I've seen that in order for material to be effective, it's very important for the students to be able to understand the content, to feel comfortable with it and be able to respond and produce results. They can similarly work with enjoyable material and other times with intriguing material, depending on the demands we have on the production of language. They become more emotionally involved when the content touches their interests, opinions, when they can make connections with their lives or when they can visualise different situations. This mostly works with speaking and writing.