Your post does not set forth sufficient facts to offer much that is specific, but in general: any teacher who commits a crime is subject not only to criminal prosecution but also to loss of employment as a public school teacher and loss of the state credential for teaching. Volitional sex acts in front of a child old enough to report the matter are almost inevitably criminal acts. If you are sure of your facts, you can make a report and complaint to the school district that employes the teacher (http://google.vesd.net/search?q=cache:56lgI_kRaA4J:pma.vesd.net/documents/policies/20050811041811-696.rtf+complaints&access=p&output=xml_no_dtd&ie=UTF-8&client=default_frontend&site=default_collection&proxystylesheet=default_frontend&oe=ISO-8859-1) and to the state Commission of Credentialing (http://www.ctc.ca.gov/educator-discipline/public.html), as well as local law enforcement. Social services does not have authority or responsibility for pushing arrest or prosecution, nor for addressing the employment and credentialing issues.
My responses to questions on Avvo are never intended as legal advice and must not be relied upon as legal advice. I give legal advice only in the course of an attorney-client relationship. Exchange of information through Avvo's Questions forum does not establish an attorney-client relationship with me. That relationship is established only by individual consultation and execution of a written agreement for legal services.
Ms. McCall is well known on this forum for her sage advice. You would do well to heed it.
The above is not intended as legal advice. The response does not constitute the creation of an attorney client relationship as this forum does not provide for a confidential communication.