Hi, Education.com offers many science fair project ideas for elementary students here: http://www.education.com/science-fair/elementary-school/

Here is a 5th grade project that can be done in 24 hours, "My Black Shirt is a Heater": http://www.education.com/science-fair/article/my-black-shirt-is-a-heater/

However, you and your daughter should peruse the collection and choose one that most interests her, and that meets your short turnaround time.

If you need a refresher on the scientific method, and want to review tips for helping your child with science fair projects, visit this info center: http://www.education.com/topic/help-child-with-science-fair-projects/

Good luck! I hope all goes well with this science exploration!