My daughter is registered for Week 3. This will be her 3rd time going. Her first time going she was 8 years old and she loved it. She went for one week last summer. We are still debating signing her up for Week 2.
She will be 13 and just finished 7th grade this summer. :)
Most do not bring sleeping bags. They prefer sheets and a blanket. Some bring padding like an eggshell pad for the mattress as they are thin. Woodward doesn't let you go around in just a sports bra, not even in the gym (although their videos towards the end of the summer indicate they are not enforcing it so much). So make sure she has t-shirts or tank tops for class and open gym.
We are from Florida, so it is still a bit cold for us. My daughter didn't go into the pool at all on her trip last summer (week 3 also). We ordered her a Woodward sweatshirt in advance and she brought leggings to wear in the cooler temp in the evenings. If she wants to horseback ride or do the ropes course, she will need sneakers. My daughter made the mistake once of going to the ropes course with sandals and was turned away for obvious reasons.
I sent her with two towels for one week. I went to the baby section of Target and bought the cheap, thin baby washcloth that if she lost or threw away it wouldn't matter. It was a six pack so she had a clean washcloth for for each day to wash her face, etc. Most girls use regular suitcases or duffle bags, not the expensive trunks you can find online for summer camp. We fly up, but if you can bring snacks, they say that is a good thing to bring. I gave my daughter a daily limit at the canteen of $12.00 per day so she could get a smoothie and a candy bar/chips.
Pack and extension cord in case her bed is not near an outlet so she can charge her phone and have her phone in her bunk (if cord is long enough). Cabins are pre-assigned, then beds are first come first serve. We pack a shower caddy for her to take into the showers with the travel size shampoos. I filled up the travel bottles bought from Target and it was more than enough for a week.
The first year we overpacked. Last summer she probably still overpacked but not quite as bad.