the worst thing i ever did

You would think a kindergarten teacher, of all people, would be able to tell the difference between a 7 and a 9. This skill is crucial in a variety of situations.
As a teacher of young children, I always try to make a big deal out of birthdays. I was always one of those summer birthday kids who never had to spend my special day at school, and I always thought it would be such a drag to have to do so. For that reason, and because everyone should be celebrated in a big way, I make a great attempt to focus on the birthday kid. Calendar Time is an important part of my daily routine. I always mark the birthdays of the current month with a special birthday cake icon and we count down to the upcoming birthday. This is always very exciting for the children and helps them have a better frame of reference, since most concepts of "time" are very fuzzy in their young minds. Yesterday, tomorrow, next week...all very confusing.
Now, this being a school story, I have to change some of the details for confidentiality's sake. So, we'll call the child Abby. Abby's birthday has been marked on the calendar as September 15 since the beginning of the month. This means we had been counting down to it for 15 days. Now, keep in mind what a big deal it is to turn 6 before most of your other classmates. Turning 6 is sort of like a right of passage because you now get to show your age with TWO hands. Big stuff. So, right away when Abby entered my classroom on Tuesday morning, I greeted her with a hug and a "Good Morning, Birthday Girl!" She grinned from ear to ear and took her seat. About one minute later she came over to me and said, "Teacher, my mom forgot it was my birthday." I instantly felt so sad. Not wanting her to feel the same, I quickly said, "Oh! I bet it snuck up on her! That happens to my mommy sometimes, too." (Yes, sometimes teachers lie.) I reassured her by reminding her that we would be celebrating all day at school. This seemed to appease her.
When Calendar Time rolled around, Abby was called to the front of the class to receive her birthday crown and glitter pencil. As the class sang "Happy Birthday" she BEAMED from ear to ear. I then always converse with the child and ask them questions about their birthday plans, so they can tell the class. I asked her if she would get a present for her birthday. "Yes," she said. I asked her what it would be. "A surprise," she said. I asked her what kind of frosting she wanted on her cake. "Pink and purple," she said. She continued on through the day reminding everyone that it was her birthday. I always try to refer to the child as "Birthday Girl" or "Birthday Boy" throughout the entire day. Every time I would do this she would whisper to her neighbor, "Teacher just called me Birthday Girl!"
At the end of the day, her 5th grade sister came down to pick her up and head home. She instantly noticed the birthday crown and said, "Who gave that to you?" "My teacher because it's my birthday," Abby said. I thought it was odd of her sister to ask that, so I continued to listen as they walked down the hall together. "It's NOT your birthday," the sister said. "Yes it is! My teacher told me!" And then I was struck with horror. What in the world was going on? I ran into the classroom, grabbed my newest class roster, scrolled down the list until I found her name, AND THERE IT WAS. BIRTHDAY: 7-15-04. why??????????? why did I read that as September????????? How do you explain to a little girl that we just celebrated a fake birthday? How do you convince her that she's not actually 6? I feared that I had caused lifelong confusion and devastation. My fears were confirmed when Dameon told me that night about his similar experience in preschool. He appears to still be scarred from it!
I tried explaining to her the next morning. She didn't seem to understand. She just kept quietly repeating these words in a whisper as she stared straight ahead, "Teacher made a mistake. Not your birthday." I felt so horrible that I had to end the conversation by saying, "You can keep the glitter pencil, though." Too late. The damage is done.