This is a great idea. Have your daughter keep track of all of her volunteer hours. My daughter loves volunteering. My daughter won the Presidential volunteer award each year since 5th grade!
Nursing homes sometimes will allow young people to go and visit, call bingo games or read. Call ahead and ask what type of help they need.
Also she could lead a group of other students in collecting games and books for the local children's hospitals.
One year they made activity bags for slightly older patients at the childrens hospital. They had word searches, cross word puzzles, mazes,pencils, jokes all geared towards the teen aged patients. They took 100 of these bags.
If she can find a scout group, sometimes she can volunteer to help their troops with projects.
She also tutored elementary children on weekends at the neighborhood library. She posted a note and told her past teachers at her old elementary school.
In the summer she volunteered 3 to 4 weeks(40 hours a week) at the local summer camp held at her old elementary school.
Some food pantries will allow kids her age to help load and unload donated food. You could also ask Churches in your community what type of service opportunities are available.
If you have charity thrift stores in the area, they will sometimes allow kids her age to help sort the goods that are donated.