Complex sentence: The junior school annex buliding was demolished in 1989, whilst additional infant school classrooms were added on in 1990 to cope with the additional capacity, a new nursery building was also added in 1990, meaning the demolition of the historic bike sheds.
Split into simpler sentences: The junior school annex building was demolished in 1989, whilst additional infant school classrooms were added on in 1990 to cope with the additional capacity. A new nursery building was also added in 1990, meaning the demolition of the historic bike sheds.