A Good Pre-Ballet Teacher
Teachers don't always have to have a full degree to become a teacher in the US. However, checking their credentials is very important! They should have some kind of biography worked up to give out, but if they don't, do not be afraid to ask.
What to Look For
A teacher should be able to break down and analyze any step so that the student can understand. Once someone told me there are three types of people in the dance world. One that can dance, one that can choreograph, and one that can teach. Now of course they can mingle, but not every dancer contains all of these factors.
Check and make sure that the teacher has those credentials. Know what training they were given, what syllabus they choose to take from, and what measure they take in making sure that the dancers are safe. In the "Ballet Companion" by Eliza Gaynor Minden she says, "Beware of a teacher who pooh-poohs health and injury preventions; she may well have a long, sad history of injured pupils If most of the class has tendinitis at the end of the term, thing twice about what's going on."