Just to add to what Melissa and Barrett have already said. We also have a large list of projects that take a short amount of time and only require household/readily available materials: http://www.sciencebuddies.org/science-f ... arents.php
I'd look at projects with a difficulty level from 1-2 if she is in 1st to 3rd grade, and from level 3-4 if she is in 4th or 5th grade. Although, if she is really interested in a project and the difficulty level is higher than that, and you think she would be able to do it, that's fine too. Our difficulty levels are only a guideline
. You can read more about the difficulty levels here: http://www.sciencebuddies.org/science-f ... ulty.shtml
We also have a Topic Selection Wizard that asks your daughter a series of questions about her interests, and then recommends projects based on what she likes, her grade level, and amount of time available: http://www.sciencebuddies.org/science-f ... gister.php
As for the experiment that was already suggested (this is the one I assume you are looking at on our website?): http://www.sciencebuddies.org/science-f ... p005.shtml
. In this case, the control group would be the one without a seed crystal, and the experimental group would be the one with a seed crystal. She would learn how crystallization occurs and the best methods for creating them.
Also, take a look at our Project Guide which gives step by step instructions on how to do a science fair project: http://www.sciencebuddies.org/science-f ... ndex.shtml
(Look at the "How to Do a Science Fair Project" section on the left side.)