This resource can be used in endless ways...
Just asking the kids to tell you everything they can about the image, will result in lots of mathematical talk. They may explore fractions just in words. They may make algebraic equations such as A+B = H+I.
The resource can go much further too. What if you tell the kids the whole area is 16? or 7? Or what if the area of A is 3? And so on.
Beyond fractions, you could ask the class to find all the lengths if the area of the large square is 25? Or 37. You'll get in to surds and pythagoras.
If you ask the students to find all the angles, then trigonometry also comes in to play.