I had the same problem with my daughter when she started Pre-K, but more so when she started first grade. For Pre-K and Kinderdarten my daughter was in a private church school and the classes were very small and the teachers were able to cater a little more to the kids individual needs. In fact her Kindergarten teacher just completely let her work at her own pace and had her working on 2nd grade work by the end of the year. When she started first grade I had to put her into public school and was completely amazed at how far ahead she was of the other kids in her class. There were some kids that did not even know how to spell or write their own names, which to tell you the truth scared me. My daughter tested for and was put into the gifted and talented program and was put into a second grade class for reading, which did help with alot of her boredom. Her scores have carried over to a new school this year and she is in the gifted and talented program again this year and is also in an advanced class and is much happier and alot more challenged.
Whatever you do, do not ever stop teaching her at home. Keep encouraging her to learn as much as she can and go as far as she can. My daughter and I play card and board games to help with counting, I give her words to spell and she reads to me every night before she goes to bed and I believe it is because we started doing these things together before she started school that she has such a desire to learn.
Talk to the teacher about your concerns and see if she is able to to anything to help with the boredom, such as extra worksheets or reading. She may be seeing the same things that your daughter is telling you and be more than happy to give you any suggestions and take any suggestions that you may have. Best of luck...
G. F.