1. Know the relevant laws applicable to your area - here in Victoria Australia teachers (as well as other named professions) are mandated reporters
2. Know/find out the workplace policy - there should be one; some may indicate the referral to the Principal
As I don't know the laws of the US I cannot comment further.
Thank you for your help!
As Tony said, check with your local laws.
Here in NYC teachers are mandated reporters with a specific hotline number to call to report issues. Per law we are not required to inform anyone before we make the call, in fact the law pretty much states we are obligated to call in the report first, before informing counselors, administration, etc (the thought being administration, counselors etc might try to talk the teacher out of making the report).
Make sure you are informed on your legal obligations and school policy. Being a new teacher you should definitely consult the school councelor and the principle. They may have knowledge about the families history and can suggest a course of action. I know first hand how damaging uninformed reporting can be. I have an son that was adopted from CPS at eight years of age. Needless to say he had a host of behavior and Psycological issues. He sees a therapist, councelor, psycholigist, and a psychiatrist. At one point my wife and I were called in by the school councelor to discuss a story he had told about a scracth he had by his ear. He was angry at me and told her I had cut him with my chain saw. We went in with his twenty five page psycological evaluation and numbers to all his doctors. They were very supportive and I'm thankfull the teacher knew enough to consult the people with years of expieriance rather than turning us over to a system that has one of the largest turnover rates and here in Texas hasn't had stellar reputation.
You should definitely find out your schools policy as how to go about reporting your concerns. Different districts may have different policies so you will want to know the correct policy so you do go about it the wrong way. If you make a mistake it could hurt your job and more importantly it could put the child in more danger.
Check with your school principal and counselor depending on your district policy. In Louisiana teachers, school staff, administrators, etc. are mandatory reporters. In addition many states protect you from lawsuit as well if you in good faith report what could possibly be abuse. Thus there would have to be evidence that abuse is present.
As a teacher especially a young teacher coming in you can run into problems calling a parent and inquiring about a child who has been allegedly abused. You would be putting yourself in a situation for a reprimand, lawsuit, or an allegation by that parent that would cause you problems and possibly the loss of your job. Now if it is a truly abusive situation you could be putting that child further in harm's way.
That is why there are specific policies present for this to prevent matters such as this. My district has a district handbook and policies and this policy is stated within that document as well as being in the faculty handbook. When you go through your new teacher training you should see this policy as the person is covering the handbook with you. If you do not see the policy then ask and they should provide you a copy of it.
Some states have a form that is filled out (which your principal or counselor should have) and a call is made to your state child protection center. You give them the basic information from the form and then fax the form to them.
However, it is best to refer to and administrator and/ or counselor. They should be aware of the policies and process for your particular district and state. As well as what indicators have to be present to actually report abuse. If you just think it is doesn't necessarily make it. If you see the signs of physical abuse or the child states or says something to that fact then you have to act upon that as a mandatory reporter. It is then passed to child protection services (following your district policies) and they investigate the matter.