Complex sentence: Construction of the 100 Pratt Road building began in the spring of 1979 and as it was not finished in time for the beginning of the 1979 school year the basement of the church building was temporarily used.
Split into simpler sentences: Construction of the 100 Pratt Road building began in the spring of 1979. As it was not finished for the beginning of the 1979 school year, the basement of the church building was temporarily used.