My dd5 starts k through k12 in a few weeks.  She came to me yesterday and was reading her Bible only asking 2 words.  She pretty much taught herself to read.  I only helped her with letter sounds previously because she had asked.  At the end of preschool last year she was only reading 3 letter words and that is the last time I worked with her.  
She also last year while I was teaching her older sister wanted to do workbooks so I gave her some of her 6 year old sisters first grade math workbooks, not expecting her to be able to to them.  She did and got 99% of it right.  
We are using k12 and I will be her main teacher but we still have to follow the state rules.  How would you go about testing where I could find out where she is at?