Hmmm...did you guess what these were?

Below you can see are all the paving slabs that make up part of the ground level playground. They go on the roof of the nursery/reception classes below.

So that there isn't a step at the classroom doors (so that it's easy to get from inside to outside) the slabs are put on these special 'legs' that wind up and down to get the height just right.

There is a big space under the slabs and this is where all the water goes when it rains.

We stayed around for a while watching the guys doing the 'setting out' of the slabs. They were ever so careful to try and get them laid out straight and square to the building and make sure that there weren't lots of silly little cut pieces.