Resign before getting fired...

[jg_nuy]

There is unfortunately a huge range of variety in these situations. There is no unitary reporting system across the nation (assuming you are in the US, forgive if not) and often even within states. In most states, schools are mandated reporters, so at least there is usually a child welfare or services investigation opened. However, quite often they are quite slow and the teacher may be able to be hired by private schools or religious schools that have more leeway in their processes.

Wishing you the best to obtain a positive outcome for your son.