Obtaining an expungement under PC 1203.4 has numerous benefits and can show future or current employers that you have rehabilitated yourself. Unfortunately, an expungement does not mean a permanent removal from your record for certain background checks, including schools.
This question (or one very similar) will be on any application for employment at all school districts in California. “Have you been convicted of, or plead guilty to, a criminal felony or misdemeanor?”
If you have a criminal conviction for a misdemeanor or felony, except for possession of marijuana or traffic infractions, the best answer is to mark the box “Yes” and explain that the charge was dismissed pursuant to PC 1203.4.
A 1203.4 dismissal does not erase a conviction as if it never occurred. Although PC 1203.4 is relief from certain "penalties and disabilities", but not all of them, including school districts.
The federal government has no obligation to recognize a 1203.4 dismissal, nor does the State of California. Although you are only applying for a position at a school, you could be considered a public official.
Public Offices are held by "Public Officials" (see Gov. Code 82048) (apparently California is one of the very few states that includes state employees in their definition of "public official"). Since employees at the School District are considered a state employees, it is best to disclose the conviction.
Furthermore, anyone applying for a professional license (teaching credential), California licensing agencies will require you to disclose a conviction even if it has been dismissed pursuant to section 1203.4.
It is better to disclose the criminal or DUI conviction than to be denied employment because you lied on your application. If you have questions or concerns regarding your conviction or eligibility for an expungement, please contact my office to discuss your specific case with me. I consistently handle expungement cases and can make sure you know all the information in order to move on from the conviction that may be holding you back.