Hi C.,
I have a 7 year old boy, and we went through this stage, maybe I can help.
This is a tough age for kids, if she's in kindergarten or 1st grade, she is adjusting to the schedules and responsibilities. Not to mention being introduced to a whole new atmosphere. Here's what we did:
First, I made sure we had nightly routines. For example, when he gets home from school I spend one one on time with him. Talking about his day, his feelings, playing games, coloring, ect. It makes him feel important and give us some special time together, also I stay connected to what's going on with him and how he's feeling/dealing. It doesn't have to be very long, I spend anywhere from a 1/2 hour to 2 hours just focusing on him, depending on time and needs of my other kids & before it gets crazy with dinner, tubs, ect.
Then we do dinner, clean up, then its tub time. Then we prepare for the next day. I do lunches, and he will help. Then we pick out clothes for the next day. I lay out "2" choices and he picks what he wants (I will also let him make special requests if there is something else he really wants to wear). Then I take breakfast requests, and lay everything out.
Then we sit down and do homework and read books every night. Then he has about a 1/2 hr-45 min to have free time. Play a game, read, watch tv, ect. And bedtime is 8:30p during the week (9:30p on Friday & Saturday nights, but only if week went well)
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In the morning, I make sure I wake them with enough time for everyone to wake up a little. I usually wake my 7 year old at 7am, school starts at 8:15a.
I gentally and calmly go in, kiss him, and tell him it's time to start our day. I sit and gentally wake him for a few minutes. With him this works for us because he wakes up calmly instead of rushed out of bed. We use humor at our house in many situations too, BUT in the morning if he was in a bad mood it only made it worse.
Because we have layed out everything the night before, mornings go smoother. (sometimes if he is fast, he gets free time to watch tv) I also made a checklist on a magnetic dry erase board, which is on our fridge. It basically lists things he has to do in order he has to do them. For example, eat, clean up area, brush teeth, wash face, get dressed, and make bed. It can be whatever, but it helps him know what he has to do and what is expected of him. He loves checking his things off himself.
If he is a morning grump, I remind him if he doesn't get happy he will lose 15 minutes at bedtime each reminder after I remind him the first time. I haven't had to remind him in a long time.
In the very beginning when I was trying to find something that worked for us, I had a happy face chart. Every morning that he was in a good mood, I placed a happy face on that day of the week, and if it went well all week, I'd let him pick our Friday night activity or take him to the video store and let him pick the movie. This helped, but he really needed a structured, consistent schedule, and to be able to wake up a little. Now sometimes activities like sports or something throw our schedule out of whack, but I try to stay as close as possible. I never have issues in the mornings now!
I apologize for this being so long, but I wanted to share what we've done, maybe give you some ideas. Basically, try to find something that fits with her personality. They say it take about a month or so to change a habit, so go slow and keep trying. Parenting is all about trial and error, and each child is different. Eventually you will find something that works for your family.
Oh and one last thing (I promise)... When she and you have a moment together and she is in a good mood, have a talk with her. Don't talk to her as a child, but like you respect her as a little person (you may already do this) and just let her know it hurts your feelings and her brother's feelings in the morning when she is grumpy or mean. Ask her how she would feel if someone was mean or grumpy to her in the morning. Ask her what makes her grumpy in the mornings, and how you might be able to help her be happywhen she wakes up. This will help her think of empathy towards others as well as feel important because you are asking her for suggestions to help her.
Ok I'm done, lol. Hope I've helped some, or at least given you some ideas on how you want to handle things. Good luck!