To get the Springfield Elementary in The Simpson: Tapped Out, you must get Lisa Simpson to unlock the quest named We Do Need Yes Education Pt. 2. Lisa Simpson will find that she is losing her abilities to speak proper English and that she is beginning to use words in the incorrect order. As a result she prays to lord, you, to build the Springfield Elementary for the children of your Tapped Out town.
To purchase and build the Springfield Elementary you need to be at least level 9 and have enough for the building which cost and handsome amount but rest assured that it is worth it. Once you have completed the building of the Springfield Elementary school you will unlock a number of quest for the children of your Tapped Out town including Milhouse and Lisa. The additional bonus to building the school is that you will also receive the legendary Principal Seymour that will surely make you lots of income from his daily jobs at school or just watching the birds.