From Kathy Schrock's Guide to Everything website:
"Screencasting is the capture all of the action on a computer screen while you are narrating. Screencasts can be made with many tools and are often used to create a tutorial or showcase student content mastery."
At Kathy Schrock's screencasting page, you can explore examples of the use of screencasts by teachers and students. She also lists several different tools available for creating your own screencasts - we will focus on two but I encourage you to try others if you wish.
Check out some resources that might provide you with ideas of how educators can utilize screencasts as both a teacher-centered and student-centered tool:
http://www.edutopia.org/blog/redefining-learning-through-screencasting-beth-holland
https://www.screencastify.com/...
https://www.teachbetter.com/bl...
