Q: I am at the end of my rope with my third and youngest child, a pretty, popular 7-year-old.

She is in constant motion. She works hard on her gymnastics team for 1 1/2 hours twice a week and does well at school.

At home, she is very difficult. She has no self-control and she is lawless. We had some marshmallows left after a bonfire and for the next two weeks she snuck up in the cupboard and ate them all. When I found the empty bag she just shrugged and said she wanted them.

Last week, she asked if she could have a soda. I refused and she went to watch TV. Later, her brother told me she had a soda.

When her big sister needed my scissors, the 7-year-old said that they were in her sister's room but this was not the truth. She had put them there and framed her sister.

Handling her is difficult enough, but I am worried the older children might start acting the same way.

A: When a child won't obey, you have to ask why, and in this case the answer is pretty clear.

You can't put three children into the same box and expect each to fit equally well. Children may have the same parents, the same lifestyle and the same diet, but they're still different and must be guided in a slightly different way.

You have to teach all of them to be honest, generous and loyal; to be fairly polite and reasonably self-disciplined; to work hard and be brave but first you have to understand--and accept--their personalities, their learning styles and their strengths of each child, especially of the youngest.

You'll bring out the best in this little girl if you look at her in a positive light. She isn't hyper. She's energetic. She's not lawless; she's a free spirit.

To encourage her kinesthetic side, give her more exercise. She not only needs gymnastics, she needs a soccer team, a bike, in-line skates and a place to swim and ice skate whenever possible.

To elicit better behavior, don't allow--or even listen to--the tattling of her sibs, and don't mention her missteps when they're around. If everyone sees her as the family problem, she will rebel more.

To help your own good behavior, put a piece of paper and a pencil in your right pocket and the same in your left pocket. Mark the right-pocket paper every time you've complimented or encouraged your child that day and mark the left-pocket paper each time you've criticized her. When you start recording more compliments than complaints, your child will begin to change.

Also, remove temptations. Don't keep sweets and sodas around if she can't resist them. Sugar makes many children nervous, tired or cranky and the caffeine in those sodas can turn them wild.

Also, read "Understanding Your Child's Temperament" (Macmillan, $23.95), by William B. Carey with Martha M. Jablow; "Understanding the Enneagram" (Houghton Mifflin, $14), by Don Richard Riso and Russ Hudson, and "The Developing Child" (Davies-Black, $13.95), by Elizabeth Murphy.

They represent three different ways to understand your daughter better. And to handle her behavior better, read "Living With the Active Alert Child" (Parenting Press, $12.95) and "Raising Your Spirited Child" (HarperCollins, $13), by Mary Sheedy Kurcinka. They'll help any parent.

Questions may be sent to margukelly@aol.com or to Box 15310, Washington, D.C. 20003.