Bliu Bliu was a website that disappeared about 10 years ago.
The key thing it had was the ability to track vocabulary AND FIND THE EXACT NEW SENTENCES as N+1 using that vocab.
Let say you know
the cat,
the mat,
sat
It will find sentences like ON to help you find “The cat sat ON the mat”
After you know that word, it will introduce a new word, always giving you just what you need.
I believe this is called N+1 learning.
IMHO, it’s a game changer.