Dear Young Christina,
I love how much you love school! That is exactly what will lead to the best choices of your life so keep that spark for learning burning bright. It's a treasure not everyone possesses.
All those hours you spend telling made up stories to your friends during recess are because you were born to be a storyteller. Don't be embarrassed by that. Kids will tease you about it but forget those kids. Keep making up stories about haunted houses and kids who make magic.
You jump from skates to your bike to a scooter and back again, and you love to play hide and seek outside. The freedom and will to do that is a gift. Kids in the generation after you will begin to lose that love of activity and exploration. Do as much of it as you can and make memories. Those will become the details that adorn your books and characters.
Continue to be observant and curious. That doesn't make you chismosa, it makes you aware and that is key when writing. You'll have that skill through adulthood so keep looking and wondering about everything and everyone around you.
Even though you find it hard to believe, your siblings will be your closest allies. While you dream of the days when you were an only child and notice the attention they get that you wish you had, buck up. In the end, you'll see that each of you hold a special place and role in the family and you are lucky to have each other.
You are a pain in the butt now and get in trouble a lot for being a smart ass but that is just your way of creating a place for yourself and exercising your voice. You don't like to feel out of control, or like your thoughts don't matter. While that gets you yelled at by your parents and they are constantly telling you to watch your mouth, I am glad that you never lose that sass. It will serve you well when you get picked on in middle school, and when you face bullies in high school. Keep talking back, just choose an audience that doesn't have the authority to pop you in the mouth.
Elementary school will be the most magical time of your life. Stop trying to rush through it. Enjoy it!