Welcome to Science Buddies. Unfortunately, I cannot pick a project for you. This is something that you have to do on your own.
In my first post on this topic, I included a link to the zoology projects on this website. Here are the specific project on cats that you could choose from:http://www.sciencebuddies.org/science-f ... g77bgclmby
And here is a project idea on stain removal. One of the challenges of this type of project is that it's difficult to measure results. http://www.sciencebuddies.org/science-f ... ml#summary
I recommend that you read carefully through all of the project ideas and decide which project you are interested in doing. You need to identify just one experiment that you can do to answer a research question. Any of the project ideas are good and could be developed into an excellent science project ..
The Science Buddies website is staffed by volunteers, and we cannot always answer immediately, but we usually try to answer within 24 hours. Please look at the upcoming deadlines for assignments due for your science project and plan to post questions ahead of time so we will have time to respond and provide you with helpful advice. Once you have selected a project, you can post any questions that you may have regarding your project.
Please post again to let us know which project idea you have decided to work on.