Description
You can create pencasts in a number of ways using different combinations of technologies. Each has weaknesses and strengths:
Virtual lectures
You might want to create small supplementary lectures and share via internet. These lectures could cover either simple or advanced topics that are usually only interesting for students with an exceptional interest or in need of extra help.
Commented model solutions
Writing model solutions to your exercises with a digital pen offers two advantages; A PDF for print without having to scan anything and at the same time a version with audio commentary which would allow students to seek more information on certain steps in the solution - information you might give in your commentary as you go along.
Guided examples
You can simply walk through examples from the textbook as you might already do on the blackboard in lectures. This will be appreciated by students who need that extra commentary on the steps in an examples in order to understand the topic - while students with no such need can simply ignore the pencast.