At parents evening last night, I was a bit to see all the groups listed up for everyone to see; in obvious ability order.
eg maths group in ascending sides (Circles, triangles, going up to hexagons), even the spelling groups go from words to thesaurus.
From the parents point of view, it is the only chance you get to really see how they are doing compared to the rest of the class, but it must be hard on the children to have it on display the whole time.
I help with crafts sometimes, so I know the lists are up all year round.