A free program for Android, by Screencast-O-Matic.

This is a free and easy-to-use screen recorder for Chromebook devices. It can record your entire screen, as well as the audio from the microphone, with or without a webcam. You can choose the recording quality, frame rate, and compression format.

You can record as much as you want without interruptions from advertisements! Audio Narration is also available, and you can even record while using picture-in-picture feature.

The main screen recording view is a timeline that you can drag to control the playback speed. You can add audio narration from the microphone and video feed from the webcam. You can also mix and match videos from multiple recordings. You can crop and trim the video to the desired aspect ratio.