Live Transcribe is a free, instant speech-to-text app for Android phones/tablets.

You can talk to your phone and it will type what you say.

Then you can copy/paste the text into a word processor on your phone like Google Docs, MSWord or just into an email.

This video will take you through how to use Live Transcribe:

Some Android devices come with it installed already.
If it is not already on your device you can download it from here:

Download Live Transcribe for your Android device.

Pick from over 70 languages to see the language that’s being spoken typed on your phone.

You can also copy and paste from this app into a document which would be invaluable to students making writing easier on the move too.