Presenting vs Practice

While I am enjoying having and taking classes integrated with technology, I wonder how Presenting a class can be vs practicing the learning.
Students usually come to class to broaden their scope of knowledge. This has been the basis of education and as far as I remember we have always told our kids; "School is fun and it is a place to learn new things".
I also do believe in Learning for Living and Living for Learning. The thing that makes me worried these days is how much learning an instructor can put into a class.
It is true that we do a lot of work, preparing for the next day class; and the fact that "the more prepared we are the less work in class is needed", but sometimes I feel individuals take this to their own advantage.
What percentage of a class can be put into Presenting and what's the balance for Practice. Now, this Practice can be anything from problem-solving topics to outcome products like essays, reports or just the solution.
When a teacher puts only 10-20% of class time on Presenting the material, the idea, the lesson and the problem; and the 80-90% of the rest to Practice, I don't think the outcome would be that wonderful.
Students especially the younger kids can be driven away with distractions, talking to each other on other topics than the issue, and wandering around aimlessly; while the teacher thinks they are working on the project!
They might not be even learning anything, because in fact nothing has been presented. Giving just a few examples and reading a copy of an article, or even opening a power point slide and skimming through the body! can not be as effective as going into the detail and heart of the lesson.
Meanwhile, if the presenting and practice style becomes too repetitive, students will be bored with what they know of the process of the lesson plan already. They won't thus take it seriously, and just do the four SSCC to pass the class or even kill the time!
ACTS must always be accompanied with innovation and irregulated expectations. That way a goal oriented instructor can be sure of the success of his/her work. We can not only count on our prepared work outside the class, then coming in and asking the kids to work on the papers. They need to hear us, they need to know that we know or not, they can go online at home and get all the info on their own timing and their own more sophisticated scholarly computers!