I am teaching with digital graphical tab and mostly a white board for solving maths and numericals of physics .However for understanding of theory , I know the importance of Ppt.I usually arrange a class like environment for the students where they can interact with me during the lecture .Nowadays days I am using Skype and a camera for focusing on board for writing.I always recommend my students to first learn theory and examples for having complete hold on topic.Being an engineer myself, I always focus on practical application of every topic.