The diagrams illustrate the reconstruction of West Park Secondary School over the 30 years since 1950. There was a unit that had been removed, while the other had been built and renovated. The school and playground position are still the same until now, with the school located on the outskirt road and the playground behind the school. The school has been expanded, so there was a science block beside the main building in 1980.
Therefore, in 1950, houses were removed to build a car park and a science block. On the other hand, farmland was reconstructed to become a sports field. However, 30 years later, the car park had been further expanded using the sports field area,. Henceforth, since 1980, the playground area had been reduced to build a sports field.
Based on the explanation above, I can conclude that the school land has been expanded in 1980 by removing houses and farmland. There was a car park expansion and also a sports field reduction in 2010.