Human beings are neurons in a greater mind: each one of our brains can transmit, receive, store, and modify information. This form we take is a functional one, it has taken us from being apex predator nomads to a civilization on the verge of exploring the cosmos. Yet, there is an inherent problem with it. When I say "tree" to you, I am not copying that image of a tree from my mental theater to you. My thoughts are translated into a phonetic pattern, which you pick up in the context of the moment.
This leads to an inherent problem with teaching. Memetic replication is not 1:1 in any current form of communication. There is always information loss or mutation. This means that a good teacher cannot say X with the expectation that their students will walk away with X in their heads. A good teacher must do Y in order for X to grow in their students' heads. Sometimes this means leading their minds along with dialogue, letting them find conclusions along the way. Other times it means setting an example for others to learn from, or giving relevant examples to make things click.
Regardless of the lesson or how it is taught, this means a teacher must be able to see from their students' eyes. Empathy is key to being a successful teacher. Empathy is our ability to simulate reality from another perspective. This insight allows us to heuristically determine how the information in our heads can be bent to be picked up from others. Thus, a good teacher is a translator. Each of us are built from our unique history of experiences, and a good teacher can see the stepping stones to scaffold any particular information to any particular student.
This leads to an important question: if empathy is important to teaching, how does one improve their empathic talents? Like crosswords improve vocabulary and running improves your endurance, the more you interact with people, the more you with reinforce those pathways in your head.
Ultimately, it boils down to perspective: how much insight can you derive about your audience? If you've only interacted with a small subgroup of people, it can be difficult to ascertain the depth of different people around you. Like traveling hilltop to hilltop will give you more viewpoints to make conclusions from, mingling with vastly different people will give you the ability to listen better to everybody.
Which leads us to a core issue we currently face as humanity. Consider the following:
Look how close-knit these two populations are. The resulting cultural reinforcement of opinion leads to a walled garden effect, where neither side hears the opinion of the other. Tribal mentality rules as communication comes to a screeching halt. This is completely detrimental to personal development, as identity defense mechanisms prevent any possible changes to the ego. Additionally, this creates an economic niche in which opportunistic individuals and groups can manipulate the easily bamboozled populations.
The solution? Be the change you want to see in the world. How? I've already said it: do Y so X is grown in their heads. Love. Listen. Be compassionate. Be a good example. This will give you the most insight to the people you're trying to reach while keeping them receptive to what you're saying. When you can see their mental landscape, it's as simple as taking them from point A to point B in the conversation. To mold the clay; the teacher takes what the student knows as they see it, and leads them to a point they can understand.
It's that whole water to wine thing. You know, that thing that one teacher could do. The more people who play this role, the closer we move to worldwide harmony.