Tile grout mixed with regular wall emulsion forms the base of these walls. After 3 coats when the wall is buffed the paint owing to the increased consistency acts like a blackboard. This was chosen over the alternative of fixing slate or using the regular black paint.
The lower half hence acts as a chalkboard and the three ropes act as display units where the children's work can be hung.
There are available coloured chalkboard paints available on special request but that requires a much larger budget since the companies will not sell you the paint. You have to hire their specialists to execute the finish on the desired walls.