"Umm, I think Genevieve is here." I said to my teacher, Mrs. Martin.
There should be a comma inbetween "Teacher" and "Mrs. Martin."
"Honey, Genevieve doesn't come 'till the end of the day," she replied.
The period should also become a comma if you're intending on using a lower case S for "She" afterwards.
Overall:
The story was a bit too short, and kind of pointless, though it was good considering you're a seven year old, but only because you're a seven year old. If I had not known of the age of the person submitting this work, I and a lot of others would have been a whole lot harder on you. You have a lot of time to grow as a writer and to fix up on somethings. I also like that you chose the name Genevieve, I plan on naming my second daughter that one day (my first daughter's name will be Tuesday).