Why do this problem?
gives the pupils opportunities to use and develop their visualising skills in conjunction with the knowledge of fractions. It's quite a contrast to just dealing with fractions numerically.
The pupils will most likely need to have had some previous experience of the shapes involved. Then the pupils can be presented with the picture or for some pupils it may be better to use the picture superimposed onto squared paper.
What shapes have you found?
How big is this shape?
Which is the biggest/smallest shape?
Tell me how you found this out?
Encourage the pupils who have well with the challenge to create their own problems for others to solve.
The should probably be plenty of resources available for many children while with others you would want them to ask for particular resources to help them. [Placing resources infront of same pupils seems to tell them that they should be using them, when you really want them to use their own ideas.]