Sacramento Unified School District Insolvency. (SCUSD) Please explain to me like I am a 5 year old.

I've lived here for 35 years and pay property taxes. I've voted on multiple actions to fund local schools. But I have to admit, I am having a great deal of trouble following the current crisis. Can someone give me a historical perspective so that I can put the day to day news in context?

Why are we at this point? What went so horribly wrong?