Please don't feel nervous about chatting to your DD's teacher about an aspect of school that is worrying her - unfortunately, very few teachers are able to read minds (in spite of the impression we may give to the children we teach!) and, a teacher won't know that a child dislikes dot-to-dot unless someone says something!
Personally I don't feel the conversation is anything to worry about...
Runoutofideas: Could I talk to you for a moment about a couple of things DD has mentioned... she's claiming she's bored at school and I've said I'd talk to you as she's worried.
Teacher: Thanks for mentioning it... could we meet at the end of today and we can chat properly? I'll keep an eye out for her today and try to keep her busy.
Teacher: DD seems to have had a good day today; lots of X, Y and Z blah blah
Runoutofideas: That sounds good! I'm not sure how to go about this without sounding like I'm interfering.... Anyway, over the holidays she said she wasn't looking forward to coming back to school because whenever she finishes her work she has to do dot-to-dot/colouring and that they are boring activities. I've asked her about her work etc. and she says she always completes everything first, gets it right etc. but as I'm not in class with her I don't know how accurate this is!
Teacher: Hmm... I don't want DD to feel bored at school either! In terms of being first to complete her work, yes, she is. However, I believe she is capable of producing work of a higher quality as she races through everything in an 'eager to please' way which, although lovely, means she's not performing to the best of her ability. Given her age I'm reluctant to ask her to re-do her work as school is about so much more than producing written work. She is capable of using capital letters and full-stops now so perhaps she would feel happier if I ask her to do X e.g. write 10 lines (instead of the expected 5)/use question marks and exclamation marks/begin to include adjectives.... etc. etc. I'll also try to reassure her that I am keen to see her best ideas, rather than the quickest ones... do you think that might help?
Runoutofideas:
Ideally, a teacher won't need to produce 'extra' work for children who finish early - if the work is differentiated properly then a range of tasks/levels of work will be completed within the same time frame. In my Y4 class I have a tray of 'extra work' which consists of various word puzzles, logic problems, science questions etc. Although the children in my class range from those who are operating at the expected level of a 5-year-old to those operating at a Y4/5 level, no-one has needed to use the 'extra work' tray because they don't finish the work I set with time to spare. The expectations for different children differ.
My own Y1 DD is performing at a level, in Literacy in particular, that is well above the rest of her class. Her teacher targets her with different types of questioning, has made it very clear that she expects a different level of writing and yet still gives her lots of opportunities for play - this is in an inner-London state primary so it's definitely possible.