I'm looking for an Android app for use on a tablet that gives access to free English language reading material suitable for a sixteen year old Thai school student to practice their English reading .

Any ideas please

What you need to find is the content the reader needs be it books, magazines, newspapers or others. One this is decided the apple to read this content will become obvious

sent from my Internet aware non fruity mobile device

A search of the Google Store yields lots of free apps, some of which appear to have access to free books / material

Sorry but you will have to search thru it yourself and see what you find

https://play.google.com/store/search?q=ebook%20readers&c=apps&price=1&hl=en