When I was a brand new, full time seminary teacher I went to a training meeting. I was eager for it. One of the men doing the training had set up, on the table in front of him, a stack of all of the resources available to us as teachers. There were resource manuals for both teacher and student. There were maps and dictionaries and volume upon volume of selected readings that would help teachers. I recognized most of it and was grateful for it. I needed all the help available to me and had studied from most of these sources. The teacher held up each one and described it and the good it could bring to the lesson. There were lots of appreciative nods.
Then he held up a set of scriptures in one hand and with his other hand pointed to all of the things on the table and said "Which do you really need?" I remember thinking that I really needed them all. He let us think about it for a bit then said "Could you teach effectively if all you had was your set of the scriptures and nothing else?" I knew at that time that it would be very difficult for me to do it that way.
Fast forward now many years ahead. Our stack on the table would be much higher. It would include not only all of the printed materials available but also everything you could find on the internet. You and I both know that we can search on the internet for anything and find mounds of information. How much of it is useful and true is open to debate but there is no debate that there is more than we can possibly study and incorporate into a lesson. So how do you decide how much to study, how much to incorporate, and how much time you will allot to your lesson preparation.
I'm going to suggest that most of what we see as resource material is not very useful in lesson preparation. It may be useful in study and pondering for ourselves, but when it comes time to prepare a specific lesson for me to teach to my specific class it is not useful. So much of what I have seen on the internet is someone else's interpretation of a lesson, someone else's idea of what the scriptures mean and how to present them. I can't teach that with any power. I can only teach with power what the Spirit teaches me to teach that day to those students.
In very real ways we cheat ourselves and our students out of a personal experience when we delay our study and preparation and then at the last minute take something that someone else has created and try to make it our own quickly. One of the great blessings of being a teacher is to have so many people from whom to 'borrow' ideas and things. I've used lots of things that I've taken from others but only after I've allowed it to soak into my thinking and given it enough pondering to own it and make it my own.
We should not allow the resources to take the place of the source and the source is the scriptures. That is where we turn and that is where we should spend the bulk of our time. Resources are useful as backups, not as the beginning of preparation. When we turn first to the source we position ourselves to be able to teach with power and authority. That will carry into the hearts of students and all will be edified of all.