PlayDate - Screencasting
Screen-Cast in the Classroom
Some considerations for teachers when creating their own tutorials or lessons using this technology as well as how to engage students in the process.
Screen casting is also a great way to provide feedback to students about their physical and digital tasks. 
Software options

The best screencasting software for teachers, is a blog post outlining options and issues with screen casting software. It's well worth a look to be informed.
The article Top 10 Best Screen Recording Software For Windows will get you started with PC versions of screen casting software. Windows 10 has a screencasting tool built in, intended for recording game play, but is useful for screen capture too.
This is FREE but requires some Java script so make sure you have updated versions. Here is a video showing how this tool works. 
5 Minute Guide to Screencasting.
There is also a series of videos to support your learning on the Screencast-O-Matic channels.

QuickTime - screen casting made easy

R & R - references and resources

Steve Dotto's video about how he creates his screen casting videos Screencasting: How I Create My Videos
Screencast-o-Matic series of Help Videos - how to start recording, set mic volume, download, draw & zoom while recording, recording both screen and webcam, publishing to google drive, saving as a video file, and advanced operations.