Screencasting is a fast and easy way to capture what is happening on your screen along with your voice or video of you speaking. Teachers can use screencasts to create self-paced lessons for students, tutorials, and supplements to sub plans. Students can use screencasting to tell stories or demonstrate their understanding of a topic or concept. There really are no limitations on screencasting can be used in schools. 

The are quite a few screencasting apps available and sometimes it is difficult to figure out which one to use. My advice is to try out a couple of different ones to see which one you are most comfortable with. All of these are free and some allow you to access additional features for no additional cost by referring friends and colleagues. All of them work nearly the same way.

This chart compares Screencastify, Screencast-o-matic, Nimbus, Soapbox, and Loom. 

Click here to see a larger version of the chart.